Z axis linear motion in a reduced engineering package

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HepcoMotion’s screw-driven linear actuator system is a vital part of the vertical feed mechanism in a bespoke, dual purpose fibre optic tower to draw fibre and canes for research

Z axis linear motion in a reduced engineering packageWhilst the commercial production of optical fibre may be in decline for telecoms applications, with copper cable increasingly the preferred alternative, considerable research effort is now being focused on a new generation of fibre optic products. And it is for this purpose that the prowess of Harlow-based Engineering Services Management (ESM) is in considerable demand on a worldwide basis.

This specialist company has recently been responsible for the design, build and installation of a bespoke, dual purpose fibre optic tower to draw fibre and canes for research. Whilst a comparable commercial system is a large steel fabricated structure, the ESM system is modular and much more compact, designed to suit the space and access restrictions of a research environment.

An essential part of the fibre optic production process for which this ESM system has been designed is the smooth, friction-free vertical feed of the glass preform, a cylindrical glass blank, into an in-line furnace. As it melts, a thin strand of silica is produced that is ultimately coated with resin for additional strength and flexibility.

A reduced engineering package from HepcoMotion forms the basis of this vertical feed mechanism. This screw-driven linear actuator system, specified for clean room conditions, comprises a Heavy Duty beam onto which is mounted a Profile Screw Driven PSD120. This product is particularly suited to Z axis applications and features HepcoMotion Herculane wheels which provide smooth, low-maintenance performance.

The PSD120 ball screw drive and linear guide are housed in a strong aluminium beam protected by a stainless steel cover strip that runs the entire length of the product to prevent ingress of dirt and debris. It is therefore a suitable alternative to a linear motion system with integral bellows that could easily cause particle contamination of a sensitive environment.

This system was designed to be a simple solution for the main tower construction, and for the purpose was supplied with joining plates for easy on-site assembly. The T-slots on the beam also provide a simple method of attachment for ancillary components.

The ball screw drive is required for small slow adjustments of the glass furnace position. System co-design and ESM Engineering Director, Mustafa Elhaggagi explains: “Extremely stable and linear movement is vital to the quality of fibre optic production. This was easily achieved with the PSD120 with some modification using standard HepcoMotion components.”

High linearity of feed movement

On the ESM ‘mini’ tower, the chuck that holds the glass preform securely as it enters the furnace is attached to an extra large carriage plate on the PSD120. And to provide the stability required to ensure high linearity of feed movement, the PSD120 was also specified with additional Utilitrak rollers to increase moment capacity and rigidity.

“For a small tower with a stroke length up to 700mm, the HepcoMotion package has proven to be an excellent choice, compact and cost effective.” Mustafa Elhaggagi continues. A further benefit for ESM was the ability of HepcoMotion to supply a complete package for easy installation and adjustment on site. Mustafa Elhaggagi adds: “ESM is a small company so the supply of this ready-to-fit, purpose built system has saved us a lot of design time.”

The first of the ESM compact fibre optic towers is now installed and operating well at the Max Planck Institute in Germany, a centre of excellence for photonics crystal fibre and soft glass fibre development. It houses a research group led by Belfast-born Professor Philip St. John Russell FRS, the eminent scientist whose extensive work in this field resulted in the realisation of photonic crystal fibres in 1996.

A second tower was delivered to the University of Malaya in Kuala Lumpur, Malaysia, in 2010 for research into flat fibres. A third tower was shipped to Brazil in February this year. Mustafa Elhaggagi says: “The research community is a close one and we mainly secure business via word of mouth,” adding that further orders are in the pipeline.

For further details about the reduced engineering package from HepcoMotion, visit the website at

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