Until now, design engineers wishing to accurately move products within a vacuum or extreme temperature environment were faced with two unpalatable choices: Be forced to design their own bespoke linear motion concept and therefore use a system which was unproven and which could create problems in terms of timescales and budgets, or they could choose to adapt from the very narrow choice of systems available with no guarantee that the materials used would meet their demands.
It now seems that an easier way is dawning! A new off-the-shelf system offers a quick and easy solution for all these linear motion, vacuum and high temperature projects.
As the markets in these areas grow, the linear motion manufacturer HepcoMotion have created a range of stainless steel linear and rotary guides which are set to revolutionise the lives of design engineers.
A vital feature of the new Hepco system is the use of stainless steel. As Chris Rees, Sales Director at Hepco says “Material selection is a key factor in this ready-made system. The reason our system works in a vacuum or high temperature environment is down to two things, material selection and some bespoke design. Vacuum environments will cause any porous materials to outgas and therefore fail catastrophically. This effectively rules out the use of any polymers, plastics and some sintered materials. Stainless steel is the default choice for a vacuum because it doesn’t outgas, is inherently clean and non-corrosive and therefore suitable for vacuum applications which require a high level of cleanliness. Stainless steel also doesn’t melt in high temperature environments.”
All of the bearings’ moving contact surfaces are made from hardened stainless steel, which is beneficial in a high vacuum environment. The quality of this carefully-selected steel ensures that performance is optimised, and wear-generated debris is eliminated so avoiding the possibility of contamination. Outgassing, is eliminated as all free spaces within the VACSS bearings are connected to a vent hole in the bottom of the retaining screw.
Another advantage of the Hepco system is that a six bearing carriage system, unlike a re-circulating ball rail system, has the ability to traverse over a large gap in the guide rail. This design allows the carriage plate (and component placed upon it) to move from the outside into the vacuum chamber and act effectively as an automated feed-in system. The gap in the rail is essential in order to allow the door of the vacuum chamber airlock to be opened and closed but the Hepco system facilitates this movement with ease and is simply demonstrated in an animated format on the Hepco website:
Grease selection is another key area of the Hepco system and it can, if the application demands it, work totally ‘dry’. The VACSS vacuum and high temperature types use Krytox LVP grease, which is rated from -15°C to +210°C, while the LTSS low temperature bearings are lubricated with AeroShell Grease 22, rated from -50°C to +150°C. The VACSS bearings can also be supplied with alternative grease or without grease if required.
Hepco’s vacuum and extreme temperature bearings are simple and cost-effective to integrate, and deliver consistently excellent results throughout a long operating life. The bearings are available as both concentric and eccentric, which extends the life of the system as when wear/play starts to develop in the system, it can simply be eliminated by adjusting the eccentric.
The bearings are available in sizes from 18 to 54 mm in diameter, with a broad range of fixing styles and load capacities from 180 to 4200 N. They have the same dimensions as the bearings in the Hepco SL2 stainless steel range of linear guides, and can be supplied ready-mounted onto an SL2 or PRT2 carriage plate, or as components that users can mount onto their own carriage assemblies.
These products are widely used in applications such as: semiconductor wafer and aerospace component manufacture; vapour deposition processes; LCD panel/ plasma display manufacture and in vacuum evaporation equipment.The LTSS bearings also appear in low temperature applications such as cold stores and specialised freeze dry equipment.
“Because of the lack of suitable solutions currently available users are forced to design their own bearing solutions for vacuum and extreme temperature applications, often at high cost” comments Chris Rees, Sales Director at HepcoMotion, “By contrast, this range of bearings will give customers a quality solution that they can simply fit, /with the confidence of achieving high performance”.
So, design engineers can now find reliable and affordable systems to save them time and money on these complex projects.
See the video of the products in action here: http://www.hepcomotion.com/en/video-vacuum-high-temperature-linear-system-pg-24-play-1182
For more information: www.hepcomotion.com