Tables provide cost-effective accuracy

Edited by the Engineeringtalk editorial team Oct 10, 2003

A cost-engineered version of the popular 400XR series of linear positioning tables is aimed at factory automation applications that do not require ultra-high positioning accuracy on every axis.

A cost-engineered version of the highly popular 400XR series of linear positioning tables is aimed specifically at factory automation applications that do not require ultra-high positioning accuracy on every axis.

The new 404XE series tables feature the same rugged construction but at significantly reduced cost; for example, a 404XE table costs 20-35% less than a comparable travel 404XR.

In addition the 404XE is compatible with the mounting arrangements of the 400XR series ballscrew tables as well as the LXR linear motor tables and they accept industry-standard stepper or servomotors.

This enables system designers and machine builders to configure mixed-technology multi-axis motion control systems easily, mixing and matching the most appropriate positioning technology on a per-axis basis, for maximum control flexibility and cost-effectiveness.

The tables are available in "short carriage" and "long carriage" configurations, to best suit the payload requirements, the short versions can accommodate normal loads up to 61kg and offer a choice of 14 different travel lengths, spanning 25 to 700mm.

The long carriage versions can handle loads up to 122kg and offer 12 different travel lengths, from 33 to 633mm.

Both are capable of repeatable bidirectional positioning to an accuracy of +/-20um, reducing to +/-30um for longer travel models.

All 404XE tables are equipped with recirculating square rail bearings and high efficiency rolled ballscrew drives, and are rated for 100% duty cycle operation.

The ballscrew drive is available with a choice of 5, 10 or 20mm pitch, enabling users to easily satisfy any desired resolution/velocity ratio.

Depending upon the chosen travel length and drive pitch selected, many of the tables can handle positioning speeds up to 1500mm/s.

All the long carriage versions can accommodate acceleration rates as high as 20m/s2.

The carriage assembly features precision dowel holes to facilitate accurate registration of the payload, and ensure highly repeatable mounting.

Multi-axis x-y and x-y-z systems can be supplied ready-pinned in order that factory orthogonality may be reproduced at customers' premises without further machining; this significantly reduces assembly costs and eliminates the risk of contaminating any of the units.

Motors can be mounted inline or in parallel with the drive shaft, the latter configuration being ideal for applications where physical length is an issue.

There are a wide variety of Oldham and bellows type couplers to transfer torque from the motor, together with a comprehensive range of motor mounting flanges and adapter plates.

Further options include fully adjustable travel limit and home sensors, and an electromagnetic brake assembly for preventing vertical carriage movement in the event of power loss.

For applications demanding relatively high positioning accuracy, the tables can be fitted with a rotary encoder or a linear position feedback device.

The 1250 lines per revolution rotary encoder attaches directly to the table's drive shaft, and is particularly useful for minimising any mechanical error when using a parallel mounted motor.

The magnetic linear position feedback device mounts directly on the table carriage and has a 5um resolution.