Technical Guide
Slideway Liner Material Compatibility: Mating Surfaces, Adhesive and Contaminants
A slideway liner is only as good as the joint that holds it, and that joint is decided by the metal it is bonded to, the finish on that metal, and what has been left on the surface before bonding. This guide covers which mating metals accept a bonded PTFE strip, what the two-part epoxy needs from the substrate, and the workshop contaminants that end a bond early.
Direct answer: the strip is compatible with almost everything, the bond is not
PTFE itself is chemically inert enough that the liner material is rarely the incompatible part of a relining job. The joint is. A bonded strip needs a metal surface that is clean, rough enough to give the adhesive something to key into, and structurally sound enough that the adhesive is bonding to metal rather than to a flaking coating. When a liner debonds in service, the cause is almost always one of those three, not the polymer.
Mating metals: what bonds and what needs extra work
| Mating metal | Bonds with standard preparation | Extra preparation it needs | What to watch for |
|---|---|---|---|
| Grey cast iron and meehanite ways | Yes, this is the standard case | Degrease, then roughen to the 0.8 to 3.2 micrometre range the adhesive is specified for | Free graphite at the surface can polish under a worn strip; machine back to clean metal rather than bonding to a burnished skin |
| Hardened and ground tool steel | Yes | Grinding marks are fine but a polished face is not; break the polish mechanically before bonding | A very smooth ground face gives the weakest mechanical key, so the roughening step cannot be skipped because the surface looks clean |
| Chromed or plated ways | Only if the plating is sound and fully bonded to the base metal | Degrease and roughen, and confirm plating adhesion first | Bonding over flaking or porous chrome produces a joint that fails at the plating interface rather than at the adhesive |
| Aluminium and its alloys | Mechanically yes | Roughen, degrease and bond soon after preparation because the oxide layer re-forms quickly | The mismatch in thermal expansion and the low surface hardness make aluminium unsuitable for a loaded machine way even where the bond holds |
| Stainless steel | Yes, with mechanical preparation | The passive layer has to be broken by abrasive preparation, not by solvent alone | A solvent-wiped stainless face can look perfect and still give a poor bond because the passive film remains |
| Bronze, brass and bearing alloys | Not recommended as a structural way face | Not applicable | Soft bearing alloys deform under the same pressure the liner is designed for, so the liner stops being the weakest link |
| Thermal spray and flame-sprayed coatings | Only after sealing | The coating is porous and has to be sealed and machined before it can carry a bond line | An unsealed spray coating wicks adhesive away from the interface and leaves a starved joint |
| A way with old liner residue | Only after full removal | Remove all old adhesive and liner, then machine or blast back to sound metal | Bonding onto a patchy old glue line reproduces the old thickness variation; see how to remove old Turcite B |
What the adhesive actually needs from the surface
The TEBAK two-part epoxy is mixed 2 : 1 resin to hardener by weight, has a pot life of about 60 minutes at 20 to 25 degrees Celsius and reaches full cure in 24 hours at room temperature. Its service range is -40 to +120 degrees Celsius. Those figures describe the cured joint, not the preparation. The preparation the same system asks for is a degreased surface roughened to Ra 0.8 to 3.2 micrometres, applied to both faces, with the strip laid treated side down and clamped evenly until cure.
Two points in that sentence decide most failures. The first is that the roughness range is a range: a mirror finish is too smooth for a mechanical key, and a coarse torn surface leaves gaps the adhesive has to fill instead of wetting. The second is even clamping. An uneven glue line becomes an uneven finished thickness, which then has to be machined out of the liner rather than the adhesive.
Contaminants that end a bond early
| Contaminant | Where it comes from | Effect on the job | What to do |
|---|---|---|---|
| Silicone spray and mould release | Shop aerosols, release agents used elsewhere in the bay | Silicone spreads by contact and destroys wetting even at trace level | Keep the bonding area free of aerosols, use fresh gloves and fresh abrasives |
| Chlorinated solvent residue | Degreasing with a chlorinated cleaner that is not fully flashed off | Residue sits in the pores and interferes with the epoxy interface | Allow full evaporation, and prefer a cleaner that leaves no residue |
| Rust preventive wax and cosmoline | Storage coating on new or re-machined parts | Wax films survive a light wipe and act as a release layer | Remove mechanically with the roughening step, not by solvent wipe alone |
| Water-based coolant residue | A machine stripped down wet | The cured liner is compatible with coolant, but dried coolant concentrate on the metal stops the bond | Wash, dry fully, then roughen; bond within the working window |
| Way oil with EP and sulphur-chlorine additives | Oil that has soaked the way for years | Compatible with the cured liner, but oil drawn out of pores during cure contaminates the joint | Degrease, then heat or allow time for trapped oil to migrate before final cleaning |
| Paint, layout ink and marker pen | Marking out or refurbishment paint on the way | Acts as a weak boundary layer between metal and adhesive | Remove before roughening and re-mark only outside the bond area |
| Graphite and molybdenum grease | Previous assembly lubricant | Solid lubricant particles remain in the surface profile after wiping | Remove with abrasive preparation and a final clean, then verify by inspection |
Temperature compatibility across the joint, not just the strip
Every layer in a relined way expands at its own rate: cast iron, the adhesive and the PTFE strip are three different materials with three different coefficients. At a steady workshop temperature the difference is absorbed by the adhesive. Near a heat source, or on an axis that runs cold and then hot, the differential movement is taken at the bond line and at the free edges, which is where lifting starts. That is why the working temperature of the joint, not only of the polymer, belongs in the specification. The thermal expansion and centre height guide deals with the measurement side of the same effect.
Recording compatibility for the job file
A compatibility record that can be checked later needs the substrate identified by name rather than by colour, the preparation method and the finish achieved, the adhesive batch and mix ratio, the clamp method and the cure time and temperature, and the ambient conditions at the time of bonding. Record the same items at the same stations as the thickness record, so that a debond two years later can be traced to preparation or to service rather than argued about.
Frequently asked questions
Can a PTFE slideway liner be bonded to aluminium?
The adhesive will bond to properly prepared aluminium, but aluminium is a poor structural way face for a loaded machine tool slide because of its low surface hardness and its thermal expansion. The compatibility question passes while the engineering question fails.
Does the liner need a primer on cast iron?
The system specified here works from a degreased, roughened metal surface without a separate primer. What it does need is that the roughening reaches sound metal rather than a burnished or contaminated skin, because the adhesive keys to the profile, not to the colour of the surface.
Is coolant a problem for the bond?
Cured epoxy and PTFE are both tolerant of normal water-based coolant in service. The risk is at the bonding stage, where dried coolant concentrate on the metal prevents wetting, so the way has to be washed, dried and roughened before the adhesive is mixed.
Can a new liner be bonded over an old glue line?
Not reliably. Any remaining old adhesive creates a thickness step and a weak boundary, and the new strip follows both. The old liner and adhesive have to be removed back to sound metal before the surface is prepared for a new bond.
Send the substrate with the specification
For a compatibility check, send the way material by name, whether the face is chromed, sprayed or previously lined, the preparation method available in the shop, the working temperature at the way, and the fluids that reach it. The TEBAK range covers the Blue PTFE slideway liner and the other colours in the same compound, the two-part epoxy adhesive specified for the 2 : 1 mix and 24 hour cure described above, and the Tuschierpaste for reading contact once the joint is cured and the face is machined. Tell us the substrate and the service conditions and we will confirm the preparation and the stocked thickness that fit the job.