Special applications may require a custom linear guide slide to fit your unique requirements. Engineers at SKF Precision Technologies have years of experience fitting slides to the most challenging applications. The following are just a few of the many special modules and slides assembled by SKF Precision Technologies for customers around the world. For information on these or other special applications, please contact SKF Precision Technologies sales engineering for personalized assistance.

Custom OEM module
Linear guide roller bearing slides are used in a 3-axis positioning module for laser-machining operations in automotive and aerospace industries. The OEM customer’s previous configuration did not meet their needs. They were looking for accuracy over the full travel envelope, not just in the machine’s "sweet spot."

Oversize ground ball screws were used in the 3-axis custom configuration to deliver rapid movements at 1000 inches per minute. The extra-long guideways for the slide component were also a key factor in the success of the project. Roller bearing guideways were chosen for their high vibration damping characteristics. The recirculating rollers provided 2.6 times the rigidity of a ball-type guideway of the same size, supplying the accuracy needed for this application. The high degree of rigidity and stability of the final design improved volumetric accuracy by 300 percent. For more information, see Idea Bulletin 2001 on the Applications, Articles and Testimonials page.

Pharmaceutical application
Linear guide roller bearing slides are being used to improve sanitation as part of a high speed, high shear, pharmaceutical granulator/mixer. A leading manufacturer of processing equipment looked to SKF Precision Technologies for some modifications to help make the transition from hydraulic to electric power on its pharmaceutical granulator/mixer. In the old design, the integral high-shear mixer bowls were raised and lowered by a hydraulic cylinder and pump.

The hydraulic fluid from these parts could possibly contaminate the process room. In the pharmaceutical industry where sterility is of extreme importance, the chance that hydraulic fluid could cause contamination led engineers to look for ways to eliminate hydraulics from the pharmaceutical granulator/mixer. The new linear guide slide needed to be driven by an electric motor and had to support a relatively heavy overhung load plus the compressive load of the rubber seal gasket. Specifically, the manufacturer looked to SKF Precision Technologies’ linear guide roller bearing slides for guiding the vertical travel movement while raising and lowering the mixing bowl.

This particular slide had a saddle width of 7", saddle length of 20", base length of 42" and saddle travel of 20". The motorized linear guide slide was driven by a rolled ball screw with overload coupling and break on input. SKF Precision Technologies provided a 5:1 right angle reducer, allowing the motor to run at a nominal speed of 1,750 RPM. These additional features were necessary to precisely control the speed of the mixer assembly, allowing it to reach the proper velocity for closure of the bowl, while not going so fast that dust from the mixture could escape.

The SKF Precision Technologies’ modifications saved time by making the machine easier to manufacture and also have kept the manufacturer in the forefront of pharmaceutical equipment design. The customer has benefited by the elimination of all hydraulic fluid, pumps and associated cylinders, virtually eliminating any chance that a sterile and expensive pharmaceutical mixture could be contaminated.

Linear motor drive slide applications
Linear motor slides are mainly used in applications where
linear guide slides with conventional rolled or ground ball
screw drives have reached their performance limits. This is
especially the case when high speed or highly dynamic and
precise positioning is required.

Typical applications are:

• Precise handling and mounting of moving objects
• Linear control units
• Movements with short stroke and high frequency
• Speed and controlled positioning
• Production, mounting and inspection
• In electronic and optical industries
• Ultra precise machining
• Automated measuring and testing equipment
• Reprographics

1. Primary unit of the linear motor
   Current-carrying coil of the motor. Integrated in the traveling top saddle.
2. Secondary unit of the linear motor
   Permanent-magnetic or toothed rail, depending on the motor type. Integrated in the stationary base.
3. Guidance
   In most linear motor drive slides, the linear guidance consists of two track rail guides, each carrying one or two guideway truck carriages. In applications where limited stroke together with high accuracy and rigidity is required, precision rail guides with crossed roller or needle rollers are used.
   For special applications linear motor slides can also be equipped with other guideways., e.g. air bearings.
4. Sensing head of the linear measuring system
   The linear measuring system is used for exact determination of the position of the saddle and in part for commutation of the motor. Generally, incremental measuring systems with a resolution ranging between 5 µm and 0.005 µm, depending upon the application, are used.
5. Linear measuring system scale
   In most linear motor tables, an open-type measuring system is incorporated in the slide, the scale being fitted in the slide base.
6. Power chain
   The cables for the primary unit and sensing head are led to the traveling saddle by a power chain.

Cross compound applications
High precision X-Z tables can be provided with either ball or roller guides.