Buying Guide
Reading a Slideway Liner Specification: Thickness, Width and Cut Edge
Most relining mistakes that look like material faults are specification faults: a thickness read as a finished dimension, a width ordered against the strip instead of the bearing land, or a tolerance that was never written down. This guide explains what each figure on a slideway liner specification actually describes and how to measure it in the shop without adding your own error.
Direct answer: three numbers, and only one of them is a purchase decision
A slideway liner specification carries a thickness, a width and a length. The thickness is the dimension the repair is built around, the width has to clear the bearing land rather than match it, and the length is a cutting decision. Reading the first as a finished dimension is the single most common specification error on a relining job, because the strip that arrives is not the thickness the machine ends up with.
What each figure describes
| Figure | What it describes | What it does not include | What it controls |
|---|---|---|---|
| Thickness | The strip as supplied, measured on the material before any bonding or machining | The adhesive layer and the material removed by milling, grinding or scraping | How much material is available to take up wear and produce a finished face |
| Width | The trimmed width of the strip across its full length | The bearing land on the machine, which is usually narrower and sometimes wider | Edge margin, adhesive squeeze-out and the pressure calculated on the real contact area |
| Length | The supplied roll length or the cut length of one strip | The length needed for the job once ends are trimmed square and grooves are cut | Waste, joins and whether the strip runs as one piece along the travel |
Three different thicknesses on one job
The number on the order, the number on the strip when it arrives and the number on the finished machine are three separate readings, and a job file should hold all three. TEBAK stocks 0.8, 1.0, 1.2, 1.6, 1.7, 2.0, 2.5, 3.0 and 3.2 mm, in widths of 100, 200, 300 and 305 mm, on rolls of 5, 10, 15 or 20 m with cut-to-length available. Those stocked steps are close together at the thin end, which is deliberate: the difference between 0.8 and 1.0 mm is often the whole finishing allowance.
| Reading | Taken when | Instrument | What it is used for |
|---|---|---|---|
| Nominal thickness | At ordering | The specification, not an instrument | Selecting the next stocked size above the required added thickness |
| As-supplied thickness | On goods-in, before bonding | Micrometer with flat anvils at three stations across the width | Confirming the strip matches the order and recording the baseline |
| Bonded assembly thickness | After cure, before machining | Micrometer or indicator on the assembly at the marked stations | Separating adhesive thickness from strip thickness |
| Finished thickness | After machining the running face | Micrometer at the same marked stations | Confirming the geometry the machine will run on |
Measuring thickness without measuring your own pressure
PTFE compresses. A caliper closed firmly on a soft strip reads low, and the same strip read by two people with different hand pressure gives two different numbers. Use a micrometer with flat anvils, close it to contact rather than to force, and take readings at the same three stations across the width every time: both edges and the centre. Record the instrument and the reading, not just a single number, because a thickness that changes between goods-in and finished measurement is information about the process rather than a defect.
Read along the length as well as across it. A strip that measures correctly at one point and low at another has a thickness variation along the roll, and that variation transfers directly into the finished face unless it is machined out. If the specification does not state a thickness tolerance in writing, ask for it before the order is placed rather than discovering the variation during finishing.
Width, bearing land and the edge margin
Order the strip wider than the bearing land so that the bond is fully supported and adhesive can squeeze out at the edge instead of being trapped under the running face. A strip ordered exactly to the land width leaves no margin for trimming, and one ordered much wider wastes material and can foul a shoulder or an oil groove. Measure the land, add the edge margin the geometry allows, and confirm the nearest stocked width. The pressure check then uses the land, not the ordered width, as the load and pressure guide explains.
Cut edge and roll memory
Skived strip is cut from a billet, so the cut edge has a slight taper and the two faces are not interchangeable: the treated side bonds, the smooth side runs. Keep the treated side identified through every handling step, because a strip bonded the wrong way round has the bonding preparation on the running face and no key at the interface. A strip taken from a roll also carries curvature. Unroll it, lay it flat, and let it relax before measuring, otherwise the curvature reads as a thickness variation at the edges.
Permanent set from storage and from service is the same family of behaviour, and the creep and permanent set guide sets out how to record it against a baseline instead of judging it from feel.
Writing the order line
A usable order line states the material, the colour where colour is used to identify the grade on the floor, the thickness, the width, the length and the edge condition. For example: PTFE slideway liner, treated one side, 1.6 mm thickness, 200 mm width, 5 m roll, square cut ends. Add the intended finished thickness and the machining allowance if the supplier is confirming the size for you, because those two numbers are what decide whether the stock size is right. The gib clearance calculation guide shows the arithmetic from measured clearance through allowance to stocked thickness.
Frequently asked questions
Is the quoted thickness the finished thickness?
No. The quoted thickness is the strip as supplied. The finished face is thinner by the material removed during milling, grinding or scraping, and the assembly is thicker by the adhesive layer, so the finished dimension has to be calculated rather than ordered directly.
Why does a caliper read lower than a micrometer on the same strip?
Because the material compresses under jaw pressure. A caliper closed by hand applies an uncontrolled load, and a soft PTFE strip deflects under it. Use flat-anvil measurement at consistent contact pressure and record the instrument with the reading.
Can two strips be joined to make up a length?
A butt joint creates a hard step on the running face and a gap for coolant and swarf, so it should be avoided on any loaded face. Order the length that runs the full travel as one piece, and use the stocked roll lengths to keep waste predictable.
Does the colour on the specification mean a different grade?
In the TEBAK range the colours come from the same compound and serve as a visual identifier on the machine floor, so the colour is not a performance grade. The thickness and the surface preparation decide the behaviour of the joint.
Confirm the size against the job, not the old strip
Send the measured clearance, the finishing allowance, the bearing land width and the length of the longest run, and the stocked size can be confirmed against the arithmetic rather than against the strip that came out of the machine. The TEBAK range covers the Blue PTFE slideway liner and the other colours in the same compound, the matching two-part epoxy adhesive, and the Tuschierpaste used to check that the finished face bears where it should.