My cutting application is set-up in a very dirty environment. Do I need to fabricate a bellows assembly to protect the unit?
Not really. Particulate contaminates rarely find a way into an Amacoil/Uhing rolling ring linear drive. Bellows assemblies are excellent protection against particulate contaminates but they can be expensive to design and build, and they often pose stacking space problems. A better, far less costly solution to meet your concern is to install "scrapers" in the shaft apertures on the linear drive. The scrapers effectively clean off any debris from the drive shaft. Scrapers are available with grease fittings for lubrication of the linear drive shaft.

Scraper-wipers mounted on either end of the linear drive prevent build up of absorbent (dust, wood/paper pulp) and non-absorbent (metal chips) particulate contaminants. With grease fittings, scraper-wipers also facilitate lubrication of the linear drive drive shaft.