Addressing slideway wear is one of the single most important factors for machine tool accuracy. If you don’t minimize the friction in your slideways, your machine won’t function properly and will ultimately lower your productivity. That being said, minimizing the friction of a slideway can be extra challenging given their proneness to stick-slip motions.
Stick-slip occurs in slideway systems that have elasticity, basically because the force needed to move a spring is different than the force needed to move the mass being pulled. This results in a “jerky” motion of the item being moved. Looking at the diagram below, for example, when a pulling force is applied to the mass, static friction from the surface prevents the object from moving right away, and instead loads the force into the spring. As the spring is stretched out and tension increases, however, the force in the spring exceeds the static friction holding the mass in place, and the mass is pulled forward in an unsmooth motion.
In order to prevent this from happening in your machines, it’s critical that manufacturers use the proper lubricants to eliminate friction and allow smooth tool movement. As a matter of fact, way lubricants are specially formulated to prevent stick-slip, while also contributing significantly to improving the production of quality parts. When choosing a way lubricant, you’ll need one that provides an extra measure of machinery protection and also satisfies the stringent demand of slideways, as the type of surface (e.g., hand-scraped, periphery ground, and cup ground), lubricant viscosity, and load on the lubricant all affect stick-slip and onset of full fluid film formation.
Choosing the right slideway lubricant for your machine tooling applications can significantly improve the production quality of your parts and prevent friction stick-slip. When choosing a lubricant for your application, here are 5 key considerations to keep in mind:
1) Machine Tool Ways and Slides Combined with Hydraulic Systems
If you use a hydraulic system with your slideways, you’re going to need a lubricant that has both the adhesive (tackiness) and protective properties of a slideway lubricant, as well as the anti-wear properties of hydraulic oil. Using these multi-functional fluids, like our own Hydro-Slide hydraulic/way lube fluid, reduces the number of lubricants you need to stock, and improves your operational efficiency.
2) OEM Recommended Fluids
Machine manufacturers make recommendations on what fluid should be used within various lubricating sumps in their products. However, just because the OEM recommends a particular fluid, doesn’t automatically mean it’s the correct selection for that machine in your particular operating environment. For example, an OEM recommended a particular hydraulic oil to lubricate the slideway of a very large machine that was suffering from extensive pitting in the operating manufacturer’s plant. Because the equipment was under warranty, the manufacturer could not switch fluids easily, even though the OEM was replacing the components every 18 months at their own cost. After working with a fluid expert, the manufacturer got approval from the OEM to switch to a waylube with higher viscosity, which solved the issue.
3) Vertical vs. Horizontal Slideways
Depending on the direction of your slideways, different adhesive properties will be required to prevent oil from being squeezed out of the ways. Especially in vertical ways, tackiness and viscosity become more important because the lubricant has a greater tendency to run-off.
4) Surface Material/Metal Type
Though you might not think it’s that important, different surface materials and metal types can have a big impact on the effectiveness of your lubricant. Different metals require different levels of lubrication, as well as certain additives that protect the metal. In order to provide maximum protection and prevent stick-slip, you must use a lubricant that’s compatible with your machine’s application. For example, if there are any non-ferrous metals in the machine, you want to be sure to use a way lubricant that contains an inhibited EP package.
5) Sought After Oil Characteristics
While lubricant formulations should be customized to fit your exact operating environment, there are several common characteristics you should look for in a way lubricant that can improve your production:
- Highly refined base oils and carefully selected anti-wear, anti-corrosion additives to reduce wear rates and protect a hydraulic system’s pumps
- Excellent lubricity and load-carrying performance
- Special “tackiness” agent to prevent sticking or chatter (i.e., chain cables that require adhesive characteristics)Waylubes that easily separate from your coolant in order to preserve the integrity of your coolant life
Need help formulating the ideal slideway lubricant for your machines? You came to the right place! Our combination of expertise, superior service, and fluid selection is unmatched in the lubrication industry. To learn more about formulating the perfect way lubricant for your operational needs, contact Tony Springer at TSpringer@uslube.com or by phone at (800) 490-4900 ext. 8823.