Diamond lapping films

Identity and construction

In 3M’s 3 mil polyester series, 661X is plain-backed and 668X adds pressure-sensitive adhesive. The adhesive attaches the film to the support. The resin on the working side holds the diamond. Allied’s standard film uses graded diamond resin-bonded to Mylar and lists cross-section and electron microscopy preparation. Allied standard diamond film

Match both the abrasive grade and the mounting variant to the order. 3M 668X

The November 2023 construction table above is typical data; grade availability varies. Its description names 676XW, but its table names 676XY. This product-identity conflict remains unresolved. 3M 600X technical data, pp. 1–2.

Grain identity also needs a product-specific basis. 3M's German 668X page identifies synthetic diamond, while Lee Valley identifies monocrystalline diamond in its own PSA polyester sheets. Neither statement establishes the crystal type, grain purity, or formulation of every diamond film. 3M 668X, Lee Valley product description.

Product forms and boundaries

A specific 3M 661X listing, ID 7000044827, identifies a 1 μm sheet measuring 9 × 11 in, or 228.6 × 279.4 mm. Grade, sheet dimensions, and product identity are separate attributes. A family name alone does not identify a supplied sheet or disc. 3M exact 1 μm sheet.

Kemet separately lists plain-backed 230 × 280 mm sheets and PSA-backed 300 mm discs in 0.5, 1, 3, 6, 9, 15, and 30 μm grades. Its broader roll table has additional grades without a named product-family key. Those broader rows do not establish additional grades for every listed sheet or disc. Kemet film and size tables.

Similar names can describe different constructions:

• CVD diamond films are diamond material. Diamond Materials supplies free-standing or frame-supported CVD diamond membranes for applications such as X-ray windows. These are not resin-bonded abrasive particles on polyester. Diamond Materials membranes.
• Metal foil is a separate abrasive form. Kemet's tooling catalog describes self-adhesive diamond-coated metal foils with galvanic bonding beside its lapping films. Metal backing and galvanic bonding are not evidence for the resin-film construction. Kemet tooling catalog, printed p. 46, PDF p. 49.
• Other mineral films remain distinct. 3M's fiber-optic brochure separates diamond films from aluminum oxide, silicon carbide, and silicon dioxide products. Its flocked polishing films can release abrasive into a slurry during use with water. That behavior does not describe every diamond film. 3M fiber-optic brochure, pp. 3–6.

Synthesis. A fixed-abrasive film is a different consumable from loose diamond powder or a separately applied diamond suspension. Coated belts also require their own backing, joint, dimensions, and attachment evidence. Shared abrasive chemistry does not establish interchangeability among these forms.

Grades, colors, and measurement bases

A micron is a micrometre, μm. A mil is 0.001 in, or 25.4 μm. Thus a nominal 3 mil backing converts to 76.2 μm. This arithmetic describes the backing alone. It does not measure the abrasive coating, PSA, release liner, or total supplied stack.

The distinctions in this table are explanatory synthesis. Kemet's claimed Ra below 1 microinch lacks a grade-specific test method and process conditions on the cited page. It is not a generic film capability. Kemet construction and finish claims.

Color is a supplier key, not an independent size measurement. Selected entries show why neither color nor a shared micron number identifies an equivalent product:

3M nominal-grade color table, p. 2, Kemet color tables.

3M repeats green for 0.1 and 30 μm, and amber for 45 and 60 μm. Its older fiber-optic brochure calls 0.5 μm diamond manila, not white. Neither a reformulation nor a universal color conversion follows. 3M 600X table, 3M fiber-optic selection guide, p. 4.

Use conditions and performance limits

Lee Valley's 3 × 6 in PSA polyester sheets can be used with water on a flat support. Its care sheet reports a preference for light oil to carry away swarf. That is supplier guidance for those sheets and sharpening applications, not permission for every coolant, solvent, adhesive, or workpiece. The cited sources do not establish universal dry-use suitability. Lee Valley care sheet, copyright 2021, 54K9601_C.

3M's ceramic fiber-connector guide names deionized water as its lubricant and labels its sequences typical starting points dependent on equipment and finish requirements. Its diamond radiusing and refinement stages are separate from final polishing with other minerals. A ferrule result does not establish a metal workpiece result, and a flat support does not define a compliant polishing pad's behavior. 3M fiber-optic guide, pp. 3–5.

Synthesis. Removal rate, usable life, residue, edge geometry, and finish depend on the complete film, support, workpiece, and process. Supplier superiority statements without matched test conditions do not establish a cross-brand ranking. Neither a nominal grade nor an advertised application proves machine fit, customer capability, or compliance with a finished-part requirement.

SDS composition and coverage limits

Allied's seven-page SDS identifies part numbers 50-30040 through 50-30442, excluding numbers ending in B. Section 3 reports polyester backing at 50–100%, cured polymeric resin at 10–less than 25%, diamond at 10–less than 25%, and dye below 0.1%. The document is printed May 6, 2015, with an April 30, 2015 review date. Its stated part range does not cover the 50-310xx discs on the cited 10 in product page. Allied SDS, sections 1 and 3.

Synthesis. These broad whole-product composition intervals do not specify diamond-grain purity, abrasive mass per area, coating thickness, adhesive construction, or a complete formulation. Their interval endpoints are not a recipe to sum. The SDS is neither a particle-size certificate nor process-performance evidence. Its age and part scope also prevent treating it as current safety evidence for every Allied film.

Reviewed October 29, 2026 PDT. The 3M 600X sheet is dated November 2023. The fiber-optic brochure bears an issued January 2009 footer, despite newer product text in the retrieved file, so its current revision history is uncertain. The Kemet catalog URL identifies 2015; its film and metal-foil coverage here is limited to printed p. 46. Undated product pages are retrieval snapshots. No lot certificate, measured particle distribution, total-stack drawing, validated process recipe, or independent comparative trial was available in this source set.

Related reference

Finishing process references discusses the distinction between edge condition and surface finish.