Linear units in general

1. What makes isel linear units different from the linear axes of other suppliers?

All linear modules are manufactured by isel in Germany and are perfectly matched to each other and to isel's linear guides. isel customers receive a complete linear system with control and motor from a single source, and special designs are also possible. Fast delivery of spare parts and a contact for all technical aspects of the linear system make isel's linear technology the all-round care package for industry and mechanical engineering.

2. How is a linear unit built?

The drive elements of CNC machines differ according to the type of application. Depending on the requirements, they are either driven by stepping motors or maintenance-free servo-motors, with step motors generally being used in simple applications and servo-motors in more demanding processes. The latest CNC machines are now also powered by linear motors.

3. How do linear axes work?

Used in industry, automation, mechanical engineering, automotive industry, medical technology, training facilities and the semiconductor industry, linear units convert a rotating movement into a linear motion. Linear units are often used in areas that require very precise work, for example in milling, dosing and lasering and 3D printing.

4. How is a linear unit designed?

Spindle pitch, spindle length and spindle diameters are among the most important criteria for the design of a linear system. Furthermore, the desired feed rate, the mass of the parts to be moved, and the vertical or linear arrangement, i.e. the position of the axes, are very important. In addition, the total length of the unit must be extended for the desired travel distance because the slides used influence the travel path. Calculation bases can be found here.

5. What are the features of a good linear unit?

Good linear axes also operate extremely precisely with high repeatability and positioning accuracy under high speed and load. They are low-maintenance, robust and extendible with other axes. For a high machine throughput, the delivery times, the speed of spare parts procurement and a simple system integration and assembly play an important role. Plug-in linear modules, as offered by isel, offer the advantage that they can be integrated into the existing system technology in no time. If the linear axis is implemented outside of machine tools, attention should also be paid to the closed nature and compactness of the linear unit.

6. How quick is linear technology?

The speed of linear units depends on the drive technology. While ball screw drives cover 250 mm per second, the speed of belt feeds is still 1 m per second. The highest speed is achieved by linear motors that can cover up to 4 m per second.

7. What is the cost of a linear unit for the metre covered?

Similar to the speed, the metre price of a linear unit also depends on the type of drive system. As a high-tech drive, the linear motor is the most expensive with a metre price of 2000 €. The price per metre for ball screw drives is between 600 € and 800 €, the belt drive is the cheapest from 300 € to 400 €.

8. What accessories are available for linear axes?

Shaft couplings, connecting angles, slide and cross table plates, coupling housing and shaft slide: The accessories for linear systems are diverse and depend on the particular application. The necessary module technology for linear units is available separately in the isel shop. So too are external limit switches, spindle support, gas pressure springs and motors with brake.

9. How are linear axes fixed?

In the aluminium profiles, the rear T-grooves are generally prepared for the fastening using sliding nuts, T-slot nuts or threaded rails.

10. What is the role of linear axes?

The rollers used for linear units are so-called linear bearings which are installed in the slide and lie directly on the guide. The balls of the bearings move close together, giving the necessary stability to the linear movement.

11. Can you build a linear unit yourself?

This depends on the size and type of the linear technology. In the hobby and model area, linear axes are often constructed by people themselves. The right linear accessories are available in the isel shop. For larger applications in mechanical engineering, industrial engineering and automation, it makes more sense to work with fully assembled linear modules.

Drive technology in linear axes

12. How are linear units driven?

A difference is made between linear units with spindle drive, belt drive and direct drive. The spindle drive and the belt drive are driven by step motors or servomotors with or without position feedback, depending on the requirements and application. These are fitted directly onto the linear units. With the isel linear systems LES 4 and LES 6, lateral and with LES 5, integrated assemblies are also possible. This ensures a space-saving integration of the motor into the machine tool. Another option is an installation with brake, on the one hand in the motor module, on the other hand in the extension of the spindle. The direct drives are linear systems with integrated linear motors. This is where the motor is located directly in the slide, hence the name Direct Drive. The magnets are mounted on the linear guide. Brakes are also available for the linear motors.

13. What is a linear unit with spindle drive?

A linear axis with spindle drive consists of a bend-resistant aluminium profile, a linear guide rail, a ball screw, a ball screw nut and a slide with continuous ball race. The rollers of the spindle and the loops of the nut are manufactured at isel, the ends of the spindle are machined and the guides are cut. An internally mounted spindle has a diameter of 16 mm in the pitches 2.5 mm, 4 mm, 5 mm, 10 mm and 20 mm. The lengths in the 100 mm grid are 290 mm - 3490 mm. The motor is assembled directly, sideways or integrated.

14. What is a belt drive?

Here, too, building is done using a bend-resistant aluminium profile, a 16 mm linear guide rail or a steel rail guide, a coil package with 3, 6, 9 or 12 coils for different feed forces, a magnetic rail and a slide with ball race. The guides can be lengthened or lined up against each other. This means that guide lengths up to 15m can be produced without any problems. On the back, there are T-slot inserts, also in a 100 mm grid. As a result, the isel linear units - depending on the customer's application - can be arranged and mounted as an axle system. The guides are lubricated for life, the maintenance intervals longer and the service life longer than in the spindle drive or frame drive. isel linear technology is available with or without motor module, with controller and software and achieves high accelerations and speeds. The path information is obtained through a parallel measuring system or directly from the magnetic strips.

15. What is a linear unit with linear motor?

Here, too, building is done using a bend-resistant aluminium profile, a 16 mm linear guide rail or a steel rail guide, a coil package with 3, 6, 9 or 12 coils for different feed forces, a magnetic rail and a slide with ball race. The guides can be lengthened or lined up against each other. This means that guide lengths up to 15m can be produced without any problems. On the back, there are T-slot inserts, also in a 100 mm grid. As a result, the isel linear units - depending on the customer's application - can be arranged and mounted as an axle system. The guides are lubricated for life, the maintenance intervals longer and the service life longer than in the spindle drive or frame drive. isel linear technology is available with or without motor module, with controller and software and achieves high accelerations and speeds. The path information is obtained through a parallel measuring system or directly from the magnetic strips.

16. By what percentage can the machine throughput be increased using isel linear motor technology?

The sophisticated linear technology behind the isel linear motors is particularly well illustrated by the example of the process plant manufacturer AP&S International GmbH, which cleans, etches, strips and develops wafers under clean room conditions. The isel DirectDrive system has achieved significantly higher speeds and positioning accuracies and good dynamics here. The service life of the linear system has been extended, while the maintenance required has been minimised. The isel-iMS magnetic length measuring system pre-mounted on the guide slide ensures the reception of the path information via the magnetic rails of the motor. The motor magnetic strip becomes part of the drive and in this way allows any extension of the linear unit. A feature that is generally not possible with other vendors. AP&S International GmbH has been able to increase its machine throughput by around 15% thanks to the advanced linear technology from isel.

17. What is a linear axis with stepper motor?

A stepper motor is the simplest drive technology and can be used both on the spindle drive and on the belt drive. With its open control path, a stepper motor is primarily used for exact positioning at low system costs. The application options range from a simple point-to-point movement to precision and synchronous movements. One of the main benefits of the stepping motor is the control without a closed control loop. The motor transmits the path or speed information coming from the control directly to the drive element without any feedback. In recent years, the stepper motor has proved to be a robust, cost-effective and reliable drive element and is therefore used in almost all industrial areas in a wide range of designs and sizes.

18. What is a linear unit with servo motor?

In the servo motor, the angular position of the motor shaft is monitored vthe event of a deviation, performs a format adjustment of the motor up to the tolerance of the target value. A path buffer can be generated by the closed control loop and the motor monitoring. Compared to stepping motor technology, higher speeds and harmonious axial ia an incremental or absolute encoder. The position of the motor shaft is transmitted to the controller and the control loop is thus closed. This compares the signal with a predefined target value and, in movements with high running stability can be achieved.

19. What is a direct drive linear system?

Linear motors are the highest-quality and fastest motors for linear units. The positioning accuracy and repeatability is in the μ-range. A linear motor is wear-free, has a long service life and is increasingly used in machine tools, positioning systems and handling systems in linear technology.

20. What is a hand wheel in linear technology?

A manual hand wheel replaces a mounted motor module. It is used for manual adjustment of the linear unit, for example changing a basic position or the exact setting of a position for which no motor is required. In industrial technology, hand wheels are now only very rarely used.

Specific linear axes

21. What are Portal Linear Units?

Portal linear units consist of 2 adjoining linear units on which an angle is mounted. Between the two angles, there is a further linear axis, which is moved back and forth between the two lower ones. The transverse axis moves from right to left, while the other two axes move from top to bottom. There is a circular movement in the flat plane. A portal unit belongs to the XYZ linear axes.

22. What is an XYZ linear unit?

An XYZ linear unit, such as the FlatCom Series XL CNC milling machine from isel, is made up of several axes. It carries out movements in different directions and can thus be used for a wide range of processes and applications.

23. What is an XY linear unit?

The XY linear axes mainly include cross tables and H layouts. Within a plane, linear tables allow an object movement in a twofold direction. Linear tables from isel contain two single-axis linear guides and can be installed one-to-one in a machine tool or as a special accessory.

24. What are vertical linear units?

Vertical linear axes move from top to bottom. People also speak of Z-axes

25. What is linear technology with distance measuring system?

In the case of linear units with a distance measuring system, these are usually linear motors or servomotors with a direct additional measuring tape on the guide, in which the motor transmits its current position to the controller. At isel, the magnetic length measuring system IMS is already installed in the guide slide (measuring head) and receives the path information via the magnetic tape, which is installed on the linear guide.

26. What is a precision linear unit?

The finer the measuring system, the higher the positioning accuracy. The most important aspect for accuracy is the measured number of pulses per revolution. The linear motor is the undisputed leader in positioning and repeatability.r.

27. Which linear technology is suitable for the clean room?

Linear motors have the best suitability. Due to the few components that can generate particles, these are the highest clean room class. In connection with clean room grease, all linear axes with spindle drive and direct drive are basically suitable for the clean room.

28. Which linear systems can be equipped with grippers?

In principle, a gripper can be mounted on each linear axis and receives the opening or closing command via the control.