Thanks to a co-design service, the company can collaborate and supports its customers in the whole production process.
The use of virtual prototyping techniques allows competing and standing out in a market turning out to be increasingly dynamic and fast. The analysis of the stamping process through the finite element simulation allows assessing the relations among the various geometrical parameters of tool equipment and the necessary magnitudes to estimate the project validity; without implementing the numerous physical prototypes that would be necessary to succeed in defining correctly a method assuring the geometrical and dimensional tolerances demanded by customers.
This characteristic allows Bora, company headquartered at Moie di Maiolati Spontini (AN) that performs the activities of design, manufacturing and maintenance of tools (besides the sheet metal stamping of components for the automotive and household appliance industries), to offer a co-design service of the component together with final customers, thus reducing critical zones already in a preliminary phase; in addition to a drastic reduction of direct costs connected with the physical prototyping (design and implementation) and of the indirect costs linked with the testing phase.
Shaping the operations for perfect results
The main problems that generally emerge depend on the shape and on the characteristics of the piece to be implemented. In particular, for components characterized by small sizes compared to the thickness and by high deformation gradients, are critical the operations that affect the formability and the thickness reduction due to the deformation.
Foreseeing already in the tool design phase what will be the thickness distribution in the finished part allows Bora to provide final customers with a forecast of how will be the piece stamped in short times.
Using finite-element virtual simulation techniques and relying on the long-term experience gained by the company in the sector, it is possible to model correctly roughing and forming operations, to propose possible modifications of the element shape to the customer. This to improve the feasibility and the attainable thicknesses in short times while providing highly reliable indications. To the ends of a correct simulation of the stamping process, the company’s technical department manages both purely geometrical aspects (such as the shape of tools), and information about the material behaviour (by which are modelled the elastic response, the work hardening, the anisotropy and the formability diagram through the data provided by the supplier of raw materials), and dynamic aspects of the tool (such as the friction between the sheet metal and the various tools, the force and the position of the elastic members controlling the blank holders).
he flexibility of the machines designed and manufactured by Atop allows implementing stators with variable shapes and sizes.
In 2016, around 800,000 electric cars were sold in the world, with the 40% rise compared to the previous year. As many as 63% of them are BEV (Battery Electric Vehicle), i.e. cars whose propulsion is directly supplied by an electric motor powered by batteries.
A more and more significant prevalence that is constantly growing; within 2020, the offer of this vehicle typology on the European market is expected almost to triple, rising from the 20 currently available models to the foreseen 54.
According to the data provided by the E-Mobility Reportstudy carried out by Energy & Strategy Group of Milan Polytechnics in 2016, it is also evident that the world market of the electric mobility is scoring impressive growth rates. To be competitive in this market it is important to bet on the technological innovation of electric-traction motors, which must be increasingly compact, lighter, with higher performances and low consumptions. Atop is specialized in supporting customers in each project phase, backing them in the achievement of this important target.
Winding and assembling line of stators with hairpin technology for prototypes and low manufacturing volumes, designed and produced by Atop.
First, the company executes an analysis of the customer’s product, which needs an engineering assessment aimed at the motor industrialization. Afterwards, it implements the prototypes that allow testing the manufacturing feasibility. Once approved the project and tested its efficiency, Atop produces the machines for the automated assembling of electric motors with hairpin technology, offering the suitable automation level for the demanded productivity.
Flexibility and performances for prototypes and small batches
The special winding hairpin technology, already integrated by Atop in fully automated lines for the production of electric motors for starter and electric- and hybrid-traction motor applications, has been further developed.
The result of the technological progress achieved allows the implementation of very flexible machines, suitable for both the development of prototypes and the mass-production with low production volumes.
The flexibility of Atop machines allows customers to produce hairpin stators with variable shapes and sizes, manufacturing with the same plant motors with different technical specifications.
The machines perform the processes of slot insulation, hairpin forming and insertion, enlargement and twisting, cutting, repositioning and laser welding of terminal wires.
Each operation is carried out with utmost precision and speed, granting an optimal control of every phase of the manufacturing process. The machines implemented by Atop grant the highest flexibility, reliability and user friendliness, exploiting as strong point the capability of offering customized solutions, aimed at satisfying customers’ specific demands, even the most complex, worldwide.
Compared to Ptfe, Meflon is formulated to provide increased efficiency, improved wear resistance, and decreased starting torque in demanding applications of food, spa, and drinkable water segments .
25During the last ten years, the market has requested sometimes to increase the operational flexibility of cooling systems using auxiliary pumps for a better control of engine cooling and efficiency, in order to meet more stringent regulations in terms of CO2 emissions. In many cases the auxiliary pumps are driven by brushless motor, regretfully still with some limited performances in terms of pump efficiency and vibrations/noise failures, as it has been for dishwasher application of this type of motor. Meccanotecnica Umbra developed a material for sliding parts such as bushings to reduce the sliding friction: the solution had been the MTU Ptfe material with appropriate fillers, Mecflon. Meflon, when compared to other grades of Ptfe, is formulated to provide increased efficiency, improved wear resistance, and decreased starting torque in demanding applications of food, spa, and drinkable water segments.  As it was for the mechanical seal of dishwasher pumps, MTU analyzed the possibility of supplying in particular bushings and rings, made with same innovative materials to prevent sticking and noise, to Tier1s and OEs that are partially replacing the traditional pumps (equipped with mechanical seals).
The irregularities of performances in real conditions are related to the occurrence of irregular flow situations and for mechanical seal, this phenomenon is bigger, because the lubricating film between the faces is typically very small. Therefore, the effect of Mecflon also for bushings has been again the key factor for avoiding sticking and noise, as it had been for traditional low power electric pumps, provided with mechanical seals.
In the past two years  MTU has got relevant progress in the definition of the project for brushless motors and has overtaken the preliminary testing activity on prototypes, with sizeable advantage also in terms of wear, and not only sticking and noise, in comparison with standard materials used for mass production.
Pumps equipped with Ptfe bushings don’t present axial wear of the front flange of the bushing and show lower wear of radial surface.
However, the combined radial wear of bushings and shaft for Mecflon Y4 solutions makes significantly lower overall damage in terms of eccentricity.
Morerecently MTU has started a specific development program for application of PTFE bushing to cooling system water pump , taking into account the typical working conditions of the automotive segment (-40/140 ° C, up to 6000 rpm, high additivated coolant, continuous operation during in-house recharge of batteries of hybrid or electric vehicles).
Operative in the winding sector for 40 years, Albe has distinguished itself for the quality of its products and its flexibility in satisfying the requirements of its clients, guaranteeing Made in Italy quality.
The experience gained over the years, combined with modern, cutting-edge equipment, allows the company to offer the best solutions and the most advantageous conditions.
The range of components in ferrite, designed horizontally, vertically, open or resined, is available in all forms (RM-EP-OLLA-ETD-ER-EC-EF-U) and for various uses: filters, transformers, elevators, pulse transformers; and responds to the various requirements of every single type of electronic circuit. Albe is an Italian company based in Cassano D’Adda (MI) and it makes products according to client specifications: open coils with or without ferrite, pillars on ferrite, sensor coils, relays, electromagnets, laminated transformers up to 20 kVA with CE, UL, Kema and Enec branding. Low profile transformers, ferrite transformers produced in all existing forms. Toroidal filters for low and high frequencies. Compensated and encapsulated toroidal coils, TA. Special Toroids, also wound with multiple wires.
The assembling phase of wound electric components can be particularly efficient if we adopt specific solutions in the connection between conductor and terminal.
TE Connectivity offers a broad range of solutions for the terminations of wound components such as electric motors, transformers, inductors, electromagnets, coils and other devices that use windings. The targets that have driven the research of new solutions should be identified not only in the cost reduction and in the quality improvement but also in the limitation of weight and size of final devices and, last but not least, in the reliability factor.
MAG-MATE terminals (bottom) and SIAMEZE terminals by TE Connectivity are solutions based on the IDC connection technology.
MAG-MATE terminals and SIAMEZE terminals by TE Connectivity are solutions based on the IDC connection technology.MAG-MATE terminals and SIAMEZE terminals are solutions based on the IDC connection technology (Insulation Displacement Connection or insulation piercing), whereas AMPLIVAR terminals operate by crimping. Both technologies do not need the pre-stripping action, as it is instead necessary in the standard welding process. In general, the wire used in the implementation of wound components is coated by a polyester film, in its turn coated by a polyamide insulating layer in case it must withstand high temperatures (around 200 °C) or, in alternative, if it must work at lower temperatures (around 150 °C), the copper wire is simply enamelled in polyurethane. In this second case, since the polyurethane has a melting point of 180 ºC, operating with welding process its removal might be unnecessary, however welding generates VOC not only owing to the contact with coating films but also in virtue of the flux contained in the alloy wire.
AMPLIVAR terminals work by crimping, providing a broad contact surface thanks to the series of sharp indentations inside the crimping chamber.
IDC and crimping processes provide the advantage of avoiding both possible cold weld joints and the exposure to an excess of temperature, besides the conductor embrittlement.
The lower wire consumption, compared to conventional processes, in the solutions proposed by TE is accompanied by the flexibility given by the possibility of using copper and aluminium wire or both simultaneously.
A glance at the market
While in the past wires generally ranged from 0.2 to 2.0 mm of diameter [AWG 32 and 12], today the demand extends to diameters under 0.18 mm (AWG 33) and exceeding 3.0 mm (AWG 9).
The thin wire is used to reduce costs and to satisfy the requisites of overall dimension decrease; therefore, also the connection system must have smaller sizes to suit narrower spaces.
Meanwhile, for several applications (for instance in wireless household appliances but the trend is generalized) is rising the demand for low-voltage energy, where lower voltages correspond to higher current to provide the requested power; consequently, the wire section grows to transport higher currents.
Mini MAG-MATE terminals by TE Connectivity can also be made of CuNiSi alloy that allows working with temperatures that reach 150 °C.
In the opinion of Ugo Aime, product manager of TE Connectivity, they estimate that still about two thirds of the wound component market exploits the hot bar welding of terminations, whereas more than one third is turning to IDC and crimping technologies.
These connection processes have proved to be an effective alternative to welding in thousands of applications, irrespective of production volumes, also because they provide the possibility of using aluminium wire, lighter and less expensive than copper, with high reliability. Aluminium allows a weight reduction because it has a minor density than copper (2.7 kg/dm3 against 8.9) and, besides, it permits a fast heat dissipation. On the other hand, it is more ductile and consequently more subjected to stretching; just for this reason, TE Connectivity has paid particular attention to the implementation of its terminals, which can also be made of CuNiSi alloy that allows working with temperatures that reach 150 °C. TE Connectivity has studied solutions that provide stable electric connections, achieved through mechanical processes that do not affect the physical and chemical properties of the wire; they originate from an approach that includes wire, dedicated systems for the connector application and know how directly generated by research.
The main market segments currently addressed by the various solutions are small and big appliances, automotive and industry.
MAG-MATE and SIAMEZE terminals
MAG-MATE and SIAMEZE terminals are assembled in plastic containers, where also the wire terminal part is inserted. They can be stamped as part of a device body or be applied.
Assembling phases of MAG-MATE and Mini MAG-MATE terminals.
Depending on the terminal type, the plastic shell can have one or two cavities intended for housing metal contacts. Containers have on the external inferior side a shaped protuberance where is laid down the terminal part of the wire crossing them. Once ended the operation of wire winding around the coil, metal contacts are inserted by pressing them into their housings, with which they lock after intercepting the wire that crosses them.
The exiting wire part is sheared with the protuberance where it is laid, by a blade integral with the metal terminal insertion. During the insertion, metal contacts engrave the insulating coating of the wire, thus establishing a sound and durable electric contact.
Assembling phases of MAG-MATE and Mini MAG-MATE terminals.
The constant pressure and the broad contact surface grant a reliable long-term connection and the conduction of notable currents.
Joints with AMPLIVAR terminal
AMPLIVAR terminals are designed as terminals of the single wires of a wound component or for their combination with other connection wires, both stiff and flexible.
With a precise crimping operation, the winding wire is automatically freed from its insulating coating, since it is forced into the internal indentations of the terminal. AMPLIVAR terminals are provided with a series of sharp indentations inside the crimping chamber and the wire is laid on these indentations (maximum three). Crimping the terminal, the tips penetrate into the insulating film of the wire, thus providing a broad contact surface.
The resulting termination assures high resistance to tensile stress, excellent electric connection and sealing against the outer environment that avoids the conductor corrosion and the entry of undesired contaminants. The crimping of AMPLIVAR terminals is executed by semi-automated presses that provide high productivity.
With AMPLIVAR models it is possible to create the termination with both aluminium and copper wire, or with a combination of both; if necessary, winding wires can be housed in the terminal with another conductor opportunely unsheathed.
AMPLIVAR terminals are designed as terminals of single wires or for their combination with other connection wires.
Route change
Copper has been for years the reference metal in the electric conduction ambit, today the replacement with the aluminium wire for a broad range of applications is the target of several producers. The potential economic saving varies according to the final product specifications and the desired efficiency requisites. If we consider a simple plastic coil with aluminium wire winding, we will obtain a significant economic impact, with a high saving on the final cost. The advantage will be much lower on more complex units, like an electric motor.
As already reported, other advantages for aluminium are lightness and good thermal conductivity but, in contrast, we deal with the difficulty in processing it. Aluminium oxide is tough and makes its welding with conventional methods difficult. An aggressive flux must be used to remove the oxide layer that would prevent the melted alloy from wetting the aluminium to form the joint.
The aluminium wire intended for windings exhibits a single drawback in the use coupled with IDC technology, owing to mechanical and environmental stresses, which cause micro-cracks and relaxation in the wire. The solution adopted by producers to reduce drastically the onset of these defects consisted in adding iron but at a higher product cost compared with the standard Al wire.
MAG-MATE terminals are designed to compensate the disadvantages of the aluminium wire without influencing its base price, weight or sealing quality.
The R&D of TE has carried out various studies to determine the factors that influence the IDC termination with aluminium wire in the long term: wire position inside the IDC connector, metal surface finish of the terminal and presence of anti-tear functions. Results witness a stable performance of MAG-MATE terminals on the aluminium wire, if during the production cycle an excess of wire has not been inserted into the terminal body, which must anyway provide for anti-tear elements in its inside. Moreover, the process must be fast, efficient, repeatable and reliable, a series of characteristics fully satisfied by the performances of MAG-MATE terminals and AMPLIVAR terminals.
The Virtual Sample Kit is a synthetic information document developed by TE Connectivity that allows identifying quickly the best combination of terminals.
The technology presented by the Concept Two by RIMAC features a double electric coupled motor, able to act on each single wheel, then with two powertrains composed by four motors.
Hypercars push the exclusivity concept to extremes: they are vehicles that are part of very limited series, with sports aesthetics and exasperate performances, by far exceeding conventional sports cars. Often, hypercars propose innovations in advance compared to the other cars and they are used as test bench to diffuse determinate technologies on more “reachable” vehicles.
We are speaking of a parallel world, of an extra-luxury market that exists thanks to an elitist niche of people looking for adrenaline, fond of motors and performances, willing to pay very high amounts to own and to drive vehicles that represent the utmost expression of the automotive technology. Hypercars satisfy on four wheels man’s natural bent for overcoming limits and it is unavoidable that such extreme cars make us dream, engaging in the design smart minds of skilful and enthusiastic engineers like Francesco Mastrandrea from AVL, the interviewee of these pages.
Hypercars are vehicles that are part of very limited series, with sports aesthetics and exasperate performances, by far exceeding traditional sports cars. In the photo a Rimac-branded hypercar.
What a hypercar is
The engineer Francesco Mastrandrea has helped us to define “hypercars”: vehicles that belong to very limited series, with sports aesthetics and exasperate performances, by far exceeding the traditional sports cars. «These cars – the engineer Mastrandrea explains us – must be framed in the context of their historical period and borders are anyway undefined. A car considered hypercar in the Eighties, like for instance the F40, today would be deemed “just” a sports car, neither with particular qualities; let us think that a current Alfa Romeo Giulia Quadrifoglio Verde, apparently a common sedan, has 510 horsepower and overall performances that exceed a hypercar dating back to 25 years ago».
At Maranello, they innovate with the hybrid “La Ferrari”: it has an all-Italian technology, with motor manufactured in Bari and electric components in Milan by Magneti Marelli.To obtain the highest possible torque, referring to the only motor is reductive but it is necessary to include the battery and the inverter, too. These elements, if not correctly sized, would represent a bottleneck for the performances that can be actually delivered.
How were they born and what is their origin? The motivation should be sought in the precise essence of man and his will of overcoming the imposed limits. There have always been people who are not satisfied with standard vehicles and the hypercar concept was devised precisely with the advent of cars; we remember that in the Sixties there were already several brands that modified “standard” cars to create unique models intended for exclusive users. «Often, hypercars propose innovations in advance compared to the other cars and they are often used as test bench to diffuse determinate technologies on more “reachable” vehicles. “LaFerrari”, for instance, with its hybrid powertrain has anticipated some years earlier the use of this technology on the rest of Ferrari range».
Often, hypercars propose innovations in advance compared to the other cars and they are often used as test bench to diffuse determinate technologies on more “reachable” vehicles. “LaFerrari”, for instance, with its hybrid powertrain has anticipated some years earlier the use of this technology on the rest of Ferrari range».Sports cars are equipped with an electronic differential that splits the torque on the two wheels of the same axle by means of small clutches assisted by hydraulic brakes, optimizing the drive dynamics. In electric cars, it is possible to manage the torque repartition more accurately and quickly thanks to the architecture with independent motors for each wheel.
Hypercar VS Supercar
If performances, very high cost and sports aesthetics might almost be shared by hypercar and supercar, there is a neatly different factor: the production modality.
Eng. Francesco Mastrandrea, Skill Team Leader Electrification AVL Italia
ZOOM ON A HYPERCAR
Among all hypercar models, the engineer Mastrandrea highlighted the excellence of C_Two by Rimac (the pronounce is Rimaz), small Croatian automotive company specialized in electric cars owned by 10% by Porsche. The vehicle has been created in the name of lightness and aerodynamics: monocoque body and roof are completely made of carbon fibre, the rest of the bodywork is a mix formed by reinforced carbon fibre and aluminium. The battery pack can develop an energy peak of 1.4 megawatt, then it is equivalent to 1,914 CV, for a maximum torque of 2,300 Nm. These values allow Rimac C_Two to accelerate from 0 to 100 km/h in 1.85 seconds (a bit optimistic) and from 0 to 300 in 11.8 seconds. All that with zero emissions and a drive autonomy of 650 km (in ideal conditions).
«I had the lucky opportunity – told us the engineer of AVL – of living some phases of the creation of these vehicles. Hypercars further heightens the exclusivity concept: very few are produced upon customers’ specific demands and a direct relationship between buyer and manufacturer often emerges, with production logics that are more similar to the ones of an expert artisan.Â
Another differentiating factor concerns the availability on the market. Sport cars, even if with long wait times and for few people, are accessible because they are anyway catalogue cars. The price as well shares in creating a gap between the supercar and the hypercar: if the cost of a sports car range from 300 to 500,000 euros, a hypercar generally starts from one million of Euro, with some small exceptions. «Not many people in the world can afford it but more than we can imagine. They have manufactured 500 Ferrari hypercars whose cost is 1.7 million Euros and they were fully booked before the production started. In this market slice everything is relative: if you have already a yacht moored at the port and other three Ferrari in the garage, spending almost 2 million Euros for a car is quite coherent, obviously in that context».
Another aspect that characterizes this segment is the second-hand market that has opposite logics to the “traditional” one”. «Recently, a Ferrari 250 GTO of 1962 was auctioned for the record figure of 48,405,000 dollars. Then, they are vehicles not affected by devaluation but, contrary to normal supercars, they gain higher value as soon as the leave the dealer».
THE FLOOR TO THE EXPERT | The electric hypercar
How much does the motor influence the acceleration of a hypercar? The acceleration is mainly linked with the torque that the traction system can deliver in the time unit, besides the characteristics of tire/asphalt and other less relevant factors like the weight distribution, asset, aerodynamics, control system and frame stiffness. To obtain the highest possible torque, referring to the only motor is reductive but it is necessary to include the battery and the inverter, too. These elements, if not correctly sized, would represent a bottleneck for the performances that can be actually delivered: it would be as if we imagined of scoring the high jump record with half of our legs’ muscles and our hands behind the back. What are the main pluses for an electrified hypercar?
Primarily, the maximum torque at zero revolutions granted by the electric propulsion that allows immediacy in the response to the impulses of the accelerator and not losing time in gear changes. I add that the centre of gravity is positioned lower than in an endothermic vehicle for the favourable positioning of the battery, with remarkable advantages linked with load transfers; this improves the longitudinal performances, then acceleration and braking. Electric hypercars are often provided with four independent motors, therefore it is possible to deliver adequate torque to each wheel and to exploit the adhesion limit of the tire, optimizing its traction qualities. The use of electronic differentials in a vehicle with endothermic motor does not allow a so efficacious control. What are instead, still today, the most critical aspects?
Mainly the weight that is strictly connected with the energy density of the battery. Today it reaches about 250 wh/kg, still not sufficient to be competitive in terms of revolution performances with an endothermic vehicle. Having two independent motors on the same axle means to have to emulate a traditional differential but with licit perplexities concerning safety: a wrong signal to one of the two motors while the vehicle is engaged in a curve can have disastrous consequences. Therefore, huge efforts are necessary in this ambit, to optimize performances and safety. If a great quality of an electric motor is the easy development of a high instantaneous power, the delivery continuity represents a critical element. Rimac hypercar, for instance, declares powers approaching 1500 kW, probably it succeeds in maintaining them just for few seconds and only under certain conditions of external temperature and battery charge. The endothermic motor, on the contrary, grants the same performance for a prolonged time, with the exception of modest variations depending on environmental conditions like temperature, pressure and relative humidity. The challenge consists in managing the cooling so that temperatures remain as slow as possible; one of the main dangers is precisely the heat released by electric components and this limit compels to declass significantly the torque delivered to wheels when you pursue the highest performances. Creating a high-performance electric vehicle is a committing, but at the same time exciting, challenge because it deals with consolidated technologies, refined in dozens of years. Certainly, the endothermic vehicle starts in advantage but we are quickly recovering». What is the next frontier?
Operation voltages exceeding 1000V and batteries at the solid state. We will see incredible things… What is your favourite hypercar?
It is the fully electric hypercar that we would like to develop here, in our technical centre, and we hope we will soon have the opportunity. We work at research and development for most of our time and it is part of our job to recognize as passable those barriers that others deem unsurmountable.
*AVL is an Austrian multinational and in Italy it has a futuristic technological hub at Cavriago, in Reggio Emilia province. The company’s activity consists in research and development on advanced powertrain systems, from traditional internal combustion engines up to purely electric motors and encompassing the revolutionary fuel cells. The ITS division of AVL works at the design and manufacturing of test benches for the test and the validation of traction systems.
Torque control: the torque vectoring
Sports cars are equipped with an electronic differential that splits the torque on the two wheels of the same axle by means of small clutches assisted by hydraulic brakes, optimizing the drive dynamics. In electric cars, it is possible to manage the torque repartition more accurately and quickly thanks to the architecture with independent motors for each wheel. The advantages of this system are partially unexplored; several companies (AVL included) are working to exploit its potentialities at best.
Drives constitute an essential part of the manufacturing sector because they are the real “muscles” of CNC machines. in this article the main typologies available on the market are analysed.
The drive is a suitable system for performing a linear or rotary motion and includes both the motor and its control system. It is possible to classify them according to the three main application fields:
Drives for the spindle rotation;
Drives for x,y, z linear axes;
Drives for circular axes
Historically, concerning the spindle, they used systems with motion transfer to belt and gears: the latter allowed achieving a transmission whereas the belt reduced vibrations. Such system assured high power and torque values but low speed values. The motion transmission could occur also through a coupling: this represented a “safety” aspect for the machine tool because, in case of anomalies, it broke down without damaging the machine. In comparison with the first case analysed, the motion transmission through coupling assured higher speeds to the detriment of powers. Precisely the electrospindle has allowed finding the right compromise in terms of speed and power (that is to say, integrated motor and spindle). This has also enabled to obtain more compactness and lower vibrations.
Motors integrated into the spindle
Until 2000, DC motors were used but with the advent of technology and a substantial improvement of power electronics (more and more powerful microprocessors and development of inverters), it was possible to introduce AC ones. Direct current motors allow a precise regulation of torque and nominal power. However, they are scarcely sturdy and rather expensive, besides needing a quite ordinary maintenance of the collector and of brushes. Moreover, they are cumbersome motors (in general, speed increases hand in hand with sizes). As time went by, alternating current motors were developed. The have discretely adjustable speed through a speed gear but they also strongly depend on frequency, as indicated in the following formula:
n = 60Â *Â f/p
where:
n= rotation speed (rpm)
f= net frequency
p=number of polar torque
A noteworthy novelty was the introduction of the inverter that, in alternating current motors, has allowed varying the net frequency, permitting to increase the variability range of the motor speed. AC motors are very reliable, simple and highly performing. In CNC machines is broadly used the so-called electrospindle, a very compact and stiff system, which allows achieving high torque and speed.
Example of Brushless motor.
Motor of linear axes
To move the linear axes of the machine tool, rotary motors are almost always used and therefore it is necessary to combine a system that transforms motion from rotary to translating. The motion transformation system is composed by a system with re-circulating ball screw in case of CNC machines and by a screw-nut screw system in case of a conventional machine. In general, the characteristics demanded to a motor for linear axes are the following, as listed below:
Each axis must be equipped with an independent drive;
Motors must be compact;
They must permit progressive speed variations;
They must have very high rapid feed speeds to reduce transients as much as possible;
High pickup and braking currents;
High accelerations.
Among the solutions most adopted, it is worth highlighting:
DC servomotor with permanent magnets. Generally, the DC motor that powers the spindle is equipped with windings on both the stator and on the rotor and therefore they are independent excitation motors. In the motor for linear axes, the windings on the stator are instead replaced with permanent magnets. Windings are mounted on the rotor and they receive electric current from brushes. The latter, however, are subjected to wear and, for that reason, they need periodic maintenance. To avoid that, “brushless” servomotors are used, in other words without brushes and with magnet on the rotor and winding on the stator part. In this way, motors become even more compact but the problem of the rotary magnetic field management emerges. Therefore, powering the winding on the stator in controlled manner becomes necessary, in order to minimize torque and speed oscillations. Hall-effect sensors are used, as they can manage the switchover of the winding on the stator as they detect the magnetic field generated by the rotor and its relative position as to the rotor. Concerning the switchover, it generates some torque instabilities called, precisely, torque ripples. The main advantages of a brushless motor, in comparison with a standard DC motor with permanent magnets, are the following:
Higher rotation speed;
Low inertias;
Inferior nominal torque to the DC one but with a maintenance of the torque itself for a much longer time;
Higher efficiencies;
Smaller overall dimensions;
Low maintenance.
2. Stepper motor. It is a synchronous motor where the rotation speed is varied by changing the frequency of control pulses. The operation is very simple: whenever the motor detects a pulse, it rotates by a certain angle. The torque in this case is not constant but it rapidly decreases as the speed rises. It is a very precise motor and therefore it grants certain result sureness. Sizes are very small.
Motors for rotary tables
Recently, they have developed linear motors that allow solving the problem of the motion transformation from rotary to linear, because approximate 15% losses occurred with the motor transformation. The linear motor is a real “linearization” of the brushless motor. It is worth noticing that the motor is as long as the axis to be driven. Therefore, magnets must be perfectly aligned. Then, we refer to:
Long inductor, when magnets are positioned on the fixed part;
Short inductor, when magnets are positioned on the mobile part.
Among the advantages, we are pointing out:
High speeds;
High accelerations;
High precisions;
High stiffness.
Nevertheless, they are affected by some relevant limits, like:
The paradigm of energy efficiency increase, branded industry 4.0, is accomplished also through the definition of spindle solutions oriented to energy saving: new scenarios at the horizon for machine tool manufacturers, which behold opportunities connected with the eco-design of the spindle subgroup and the advent of innovative direct-drive solutions.
Manufacturing represents one of the industrial sectors characterized by a high energy demand: for this reason, national and European institutions, universities, industrial associations, regulatory bodies and companies have started – at different levels and each with its own role – introducing policies, directives and solutions oriented to increase the sector efficiency. Various studies and works carried out on stock removal machine tools have highlighted how a potential energy saving can be achieved through opportune design choices aimed at the use of more efficient technologies and components and at a better machine use in terms of definition of operating parameters and/or machining strategy. In the specific case, the present article focuses on the aspects of efficiency and energy consumptions of the spindle systems that equip CNC machining centres. The current developments referred to the spindle/electrospindle ambit are mainly aimed at the enhancement of static, dynamic (stability, vibrations, chatter, removal capacity and so on) and productive performances of such machine elements, however paying growing attention to “eco” and energy consumption aspects. It is in fact worth underlining that the spindle, together with the relative auxiliary systems, constitutes one of the main energy-eater machine components in use phase, during the execution of machining processes for the manufacturing of finished products.
Spindle system and operating conditions
Spindles are rotary elements generally designed and manufactured for a broad array of machine tools used in several application sectors (aerospace, automotive, etc.) with the general target of maximising the stock removal rate and accuracy, consistently with the existing constraints. Since NC machining centres generally need to execute several machining operations on the same workpiece, the spindle system must be suitably designed for assuring the demanded flexibility level and the desired performances (speed, torque, power and accuracy) within the wide range of admissible operational conditions.
Energy saving and direct-drive spindles
Speaking of eco-oriented design of machine tool electrospindles, it is useful to highlight also the potentialities offered by the adoption of specific direct-drive spindles. Relevant example is represented by the result of the pre-competitive research and development activity carried out in the ambit of Erod project, funded by MiSE, with the participation of Milan Polytechnics, the manufacturer of HSD spindles and the manufacturer of machine tools Jobs Spa. Such activity has led to the development of an innovative direct-drive spindle and to the comparison of the latter’s energy performances with those provided by a standard mechanical spindle. The examination is specifically focused on Jobs Jomax 265 machining centre, analysed in terms of energy consumption in two different configurations: with a mechanical spindle typically used in a broad range of machine families by Jobs Spa and with innovative solution of direct-drive spindle opportunely designed. The traditional solution consists of an asynchronous electric motor, Redex Andantex transmission with two speed ranges (direct one and one providing for the spindle speed reduction to 1/5 of the motor rotation one), one chiller for the electric motor cooling and one unit constituted by an oil circulation pump and a second chiller for the relative conditioning. Such mechanical spindle can deliver torque exceeding 1000Nm and perform machining up to 4000rpm. The “innovative” solution is instead composed by a high-efficiency electrospindle intended for multitasking machines, i.e. to be used for performing both high torque/low speed machining and high-speed machining operations. This provides for the replacement of the above-mentioned asynchronous motor with a synchronous motor purposely designed and equipped with electronic speed gear. This solution allows neatly simplifying the system and, compared with the traditional solution adopted as benchmark, only the electric motor chiller is conserved. More in detail, the direct-drive spindle can cover an analogue speed range (max. speed 6000rpm) in virtue of a double configuration of stator windings that can be opportunely selected in relation to the technological requirements of the machining to be carried out. From the point of view of the maximum available torque as well, the performances of the new spindle motor are comparable to the conventional solution’s. From the energy point of view, the direct-drive solution, characterized by a drastic system simplification, aims at decreasing the consumptions connected with the presence of the lubrication system, the conditioning of the speed gear oil and, obviously, at eliminating its losses. On the other hand, however, the synchronous electric motor, having to operate on such a broad speed range, will hardly exhibit high efficiency performance, comparable to the asynchronous solution’s. The interesting design aspect is then the analysis of energy advantages and drawbacks of the two spindle solutions in comparison, targeted to quantifying the energy saving associated to the replacement of the standard spindle with the direct-drive one in a typical day of use of the considered machining centre.
Electrospindles and efficiency maps
Let us consider, as an example, a machining centre for milling operations: a relevant percentage of the energy consumption is connected with the spindle, depending on the torque and rotation speed demanded by the process. If an electrospindle is used, it is fundamental to consider also the consumption of the chiller that cools motor windings: the coolant circulation pump determines an important contribution to the “basal consumption” (independent from the various activities executed by the machine). In this case, the efficiency of the spindle + chiller subsystem can be defined as ratio between the output mechanical power from the spindle (towards the process) and the overall electric power absorbed by spindle and chiller, which is function of the demanded load. Such efficiency can be assessed experimentally through power measurements carried out by subjecting the spindle to different combinations of torque and speed, thus achieving a mapping. Then, it is possible to distinguish:
acceleration/deceleration phases related to the spindle start and stop (that actually use the whole available power)
parting off/facing machining (at growing speed, with the decreasing radius)
The brushless motor used would reach 95% of efficiency close to the high-torque region and lower speeds than defluxion one. The chiller action damages low-torque “zones”: since the majority of the test cycle examined occurs in regions with efficiency in the 20-70% range, the overall efficiency produced is much lower than the theoretical maximum. Hence, we therefore infer an indication for machine tool manufacturers: in designing a machine, it is important to evaluate the spindle system efficiency (with the eventual addition of the chiller and other auxiliaries) compared to the real requirements of the user regarding the machining cycles to be executed, in terms of speed and torque to be delivered. Moreover, it is desirable that the regulation activity concerning the evaluation of the environmental impact of machine tools – promoted by ISO WG12 and, on a national scale, by the relative UNI work group –can lead to standards for the definition of tests of “machine-based” energy measurements, aimed at a characterization, even simplified, of such efficiency maps: the goal is prescribing the execution of measurements that “sample” the efficiency in some reference points.
In Europe, the 640/2009 Regulation on electric asynchronous motors, which has been transposed in more phases, has been in force for some years now. Currently, the regulation concerns 50 Hz or 50Hz/60Hz three-phase asynchronous motors, for constant operation, with nominal powers between 0.75 kW and 375 kW, with 2, 4 and 6 poles; the energy efficiency class for use in net must be minimum IE3 for them.
The new DRN motors constitute integral part of our modular system of motors. A new interface with mechanical reducer, able to assure higher flexibility and system combination. With optimized weight, sizes and efficiency, these asynchronous motors can be easily integrated into machines and plants for high energy-efficiency operation. The new IE3 motors are naturally compliant with all main global specifications and design regulations like IEC 60034, NEMA MG1, UL 1004-1, CSA C22.2-100, ABNT 17094-1 and GB 12350 (CCC). Moreover, they already conform to the next regulations in the energy efficiency field for Europe, India, Brazil, USA, Canada, China and other Countries.
All this makes Sew-Eurodrive an outstanding manufacturer of low energy consumption gearmotors of the IE3 efficiency class, with nominal powers included between 90 and 200 watts, with all customary quality and a complete line of services connected with the product that operators know and appreciate.
The main product types that will feature in the Parsons Peebles standard product portfolio include the PPD series, an IC411 motor which is a self-ventilating, enclosed machine with external fins and an external shaft mounted fan. The PPT Series is an IC611 motor which is also an enclosed machine and has a built on heat exchanger and shaft mounted fans. The PPC Series, an ICO1 motor, is a self-ventilating machine that is integral fan cooled by a shaft mounted fan. These all conform to the IC code as laid down in 60034-6.
The three-phase squirrel caged induction designs, come in a range of voltages, most commonly 3.3kV, 6.6KV and 11kV with class F insulation and class B rise as standard. The product range covers 2 to 10 poles in sizes up to 560 frame, across a power range of 185kW to 2.8MW.
The introduction of the standard product range to the Parsons Peebles portfolio widens the opportunity of the company offering to many markets including the process industry, cement & aggregates, metals and water and wastewater treatment. Parsons Peebles are already very active in these industries through its acquisitions of service companies, Anstee & Ware and Taylor and Goodman, who have many years of experience in servicing electrical and mechanical machines such as LV/MV/HV motors, pumps, gearboxes and air compressors. The new Parsons Peebles standard product range will be sure to further compliment the business’s offering and support these markets more extensively.
Meflon, when compared to other grades of Ptfe, is formulated to provide increased efficiency, improved wear resistance, and decreased starting torque in demanding applications of food, spa, and drinkable water segments.  As it was for the mechanical seal of dishwasher pumps, MTU analyzed the possibility of supplying in particular bushings and rings, made with same innovative materials to prevent sticking and noise, to Tier1s and OEs that are partially replacing the traditional pumps (equipped with mechanical seals).
Albe is an Italian company based in Cassano D’Adda (MI) and it makes products according to client specifications: open coils with or without ferrite, pillars on ferrite, sensor coils, relays, electromagnets, laminated transformers up to 20 kVA with CE, UL, Kema and Enec branding. Low profile transformers, ferrite transformers produced in all existing forms. Toroidal filters for low and high frequencies. Compensated and encapsulated toroidal coils, TA. Special Toroids, also wound with multiple wires.
TE Connectivity has studied solutions that provide stable electric connections, achieved through mechanical processes that do not affect the physical and chemical properties of the wire; they originate from an approach that includes wire, dedicated systems for the connector application and know how directly generated by research.
