FAQ

What is a flat flex cable?

A flat flex cable is a type of cable specifically designed for high flex applications. The conductors are specially formed to resist cracking and are surrounded by a polyester insulation layer. This insulation is designed for high flex applications and is very abrasion resistant. Special circuit boards provide a means to make a good electrical connection on both ends.

The flat flex cable lends itself well to positioning stages in several ways. First, positioning stages require that all internal cables must have a tight bend radius. Copper wires in round cables will fail much faster in tight radius applications than flat flex cables. The conductors in a round cable have a different radius to travel depending on their position in the cable. This causes the conductors to go into tension and compression during each cycle, accelerating the failure of the cable. A flat flex cable insures that all the conductors bend along the same radius, reducing tension and compression forces. In addition, the insulation in a round cable is typically not designed for abrasive applications. The tight space inside a positioning stage dictates that the cable will rub up against a hard surface all the time. Insulation not designed for abrasion will fail quickly. Third, positioning stages require electrical isolation between high and low power signals. Flat flex cables can easily be isolated from one another with almost no impact on the space requirements. Shielding high and low power round cables from one another has a large impact on the required space. Fourth, positioning stages have many signals, up to 17 signals for a linear motor driven positioning stage. Since most of those signals are low level, and the flex flat cable can be designed with very narrow conductors, a maximum of two flex circuits are necessary to carry all the signals, as compared to 17 individual wires.

Do you have problems with noise coupling between the power and feedback flex cables?

As in all cable management systems, care must be taken to isolate high and low level signals to prevent cross-coupling of noise. Primatics has taken steps to electrically isolate the flex cables from each other to minimize noise problems.

Are the flexible flat cables susceptible to melting in peak current conditions?

All cables follow a simple rule: the maximum current a conductor can carry before failure is proportional to the cross section of the copper in the conductor. Flexible flat cables are no different. We have designed our flex cables to be able to withstand the maximum current draw of the motor without damage.

Do all the positioning stages in a family have the same dimensions?

The PLG110, PLG160 and PLG210 are considered separate stage families. The in-line, frameless, parallel and linear motor versions of each family of tables have identical height and width dimensions, but the total length varies slightly depending on the model. Although the body of the parallel mount stage has identical dimensions to the others, the motor mount itself is 60mm wider than the rest of the stage.

How does a frameless motor work?

A frameless motor works exactly the same as a brushless servomotor. The only difference is that the rotor magnets are placed on the ballscrew shaft where a motor coupler would ordinarily go. The ballscrew acts as the motor's rotor. This improves the dynamic response of the stage since a compliant coupler is no longer in the system. In addition, the stage is shortened by several inches.
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Can Primatics do custom products?

Primatics can do custom products based on our current product offering or design something completely new. The most common customizations are special mounting holes, travel lengths and multi-axis assemblies. In addition, special carriages to accommodate more powerful linear motors are common.
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How do I adjust the limit and home switch placement?

The home and limit switch placement is typically done at the factory. Field changes are possible by removing the top cover of the positioning stage. The limit and home positions are triggered off an adhesive label in the interior of the positioning stage. The label is located on the left side of the positioning stage as you look down it from the motor end. The transition from white to black on the label signifies the position of the switch. Changing the position of the transition changes the position of the switch. Primatics can provide blank labels and instructions for field changes.

How do I re-lubricate my positioning stage?

Removing the side plates gives you full access to the grease ports of both the linear guides and ballscrew.

How do I mount your tables XY? XYZ?

The mounting hole patterns on the carriage are designed to accommodate XY mounting of positioning stages in the same series. Adapter plates are available to match stages of different sizes, as well as assemble XYZ systems. In addition, all axes can be pinned for precision alignment.
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Can I run a linear motor driven stage vertically?

It is not advisable to run a linear motor stage vertically. A loss of power will cause the carriage to free fall since a linear motor stage is virtually frictionless. In addition, the force of gravity must always be overcome, which puts a large continuous force requirement on the motor. Linear motors can overheat quickly when run vertically.

Can I add a cable carrier?

Externally mounted cable carriers are available for multi-axis assemblies.

Can I add more axes to my drive chassis in the future?

Primatics MDC drive chassis can accommodate 2, 4 or 8 axis of amplifiers. A four axis MDC with two axes connected has room to add two additional axes at a later date. If a four axis box needed to be expanded to five axes, an eight axis box would be necessary. Care must be taken to ensure the power supply is sufficient to meet the needs of the additional axes.

How long does it take to adapt your drive chassis to a new controller?

The time to adapt the MDC drive chassis to a new controller will vary depending on the backlog, however most adaptations take no more than four weeks. The customer must supply us with a sample controller and documentation.

Can I get custom motor mounts?

Customer motor mounts and adapter plates are available. The customer needs to supply a drawing of the motor to be mounted. Custom motor mounts add about four weeks to the standard delivery time.
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