Get A Quote

Diamond Turning Optical Mold Inserts

Diamond Turning Optical Mold Inserts

Diamond Turning Optical Mold Inserts

Controlled Form and Mirror Finish in One Cut.

YISHUN provides diamond turning optical mold inserts for suitable rotational, concentric and plated optical structures. The goal is not simply a bright surface. It is to generate the required form, center relationship and surface finish in one controlled machining route.

Send Drawings for Review See Real Production Evidence
RotationalBest suited to axisymmetric, circular and concentric optical geometry.
Material-firstThe substrate or plating route is confirmed before the final cutting plan.
Form + finishSurface quality is evaluated together with profile, center and edge condition.
Finished mirror optical mold insert set with bright reflective surfaces
Real finished mirror inserts from YISHUN production material. Exact geometry, material and end use remain subject to the customer drawing.
Three decisions before cutting starts.
Is the geometry suitable?Rotationally symmetric or concentric structures are the strongest candidates. Non-rotational surfaces may need five-axis machining or another route.
Is the material diamond-turnable?Aluminum, copper, brass and qualified nickel-phosphorus surfaces are common candidates. Ferrous mold steel needs a different route or compatible plating.
How will it be accepted?Profile, roughness, feed marks, center condition, edge quality and datum relationships must be defined—not just visual brightness.
Real YISHUN production evidence

A real diamond turning operation—from the rotating workpiece to finished mirror inserts.

These images outline a typical diamond turning workflow: a mirror insert mounted on the spindle, the cutting tool approaching the optical surface, and a matched set of finished inserts. Together they help explain how surface condition, tool access and rotational geometry are reviewed on this page.

Real diamond turning operation on YISHUN optical mold insert
Real YISHUN diamond turning operation: rotating optical insert, spindle setup and cutting tool in the machining area.

What this real process evidence confirms

Workpiece setupThe optical insert is mounted on a rotary spindle, with the mirror surface presented to the precision cutting tool.
Machining routeThe process uses controlled rotational cutting rather than broad manual polishing to generate the optical surface.
Visible resultThe finished inserts show highly reflective surfaces and repeatable external geometry across multiple pieces.
Critical controlsTool position, spindle behavior, center transition, feed marks, effective aperture, edge condition and datum relationships remain project-critical.
Evidence boundaryThe images confirm real YISHUN production and finished inserts. Material grade, profile tolerance, roughness and application must still be confirmed from project documentation.
The page therefore uses these frames as authentic machining evidence, while avoiding unsupported claims about the final product application or universal achievable values.
≤0.1 μmForm accuracy referenceEquipment-sheet reference for the 250UPL, subject to project conditions.
≤2.0 nmRoughness referenceEquipment-sheet reference, not an automatic result for every material or geometry.
300 × 200 mmMachine travel referenceUsed for early envelope and setup evaluation.
50–10,000 rpmSpindle range referenceActual cutting parameters are selected after material and tool review.
Common sourcing failures

A mirror surface can still fail the optical insert.

Most problems begin before the finishing pass. The wrong material route, unstable pre-form, unclear effective aperture or undefined inspection method can create a surface that looks bright but does not function as intended.

Wrong material route

Direct diamond turning on an unsuitable ferrous surface can cause rapid tool wear, unstable cutting and schedule loss.

Center and feed-mark defects

Concentric marks, center artifacts or periodic texture may affect reflection, stray light or replication even when the surface appears smooth.

Profile lost after polishing

Uncontrolled post-polishing can reduce roughness while changing sag, groove shape, edge definition or the effective optical zone.

Datum mismatch

The optical surface may pass local measurement but still fail assembly if the center, flange, seating face or reference diameter shifts.

What we evaluate

Diamond turning optical mold inserts for suitable optical geometry.

We do not force every insert into SPDT. Each drawing is reviewed for rotational symmetry, tool access, center geometry, substrate, plating, effective aperture and measurement feasibility.

Real close-up of rotating optical mold insert and diamond cutting tool

Rotational mirror optical inserts

Real close-up of a rotating mirror insert during precision turning, showing the optical surface and tool-access relationship.

Actual multi-cavity mirror optical mold insert set from YISHUN

Multi-cavity mirror insert sets

Actual YISHUN product image showing repeated mirror-finish optical pockets, used to review cavity consistency and surrounding structural features together.

Actual circular optical mold insert with multiple feature positions and mirror surface

Circular inserts with multiple feature positions

Real circular insert image used to show rotational optical geometry where the mirror area, datum ring and multiple surrounding feature positions must be reviewed together.

Flat and annular optical surfaces

Qualified flat, ring-shaped and annular insert surfaces with specified datum and functional zones.

Nickel-phosphorus plated inserts

Substrates prepared and plated for a diamond-compatible optical cutting surface, subject to plating review.

Prototype and replacement inserts

New development inserts, validation parts and replacement inserts where matching and repeatability matter.

Material and route selection

The cutting route starts with the substrate—not with the machine.

Diamond turning optical mold inserts requires a material surface that can be cut stably without damaging the tool or creating unstable texture. For steel-based tooling, the plating route and pre-form quality become part of the optical result.

Aluminum alloysDirect SPDT candidateCommonly suitable for reflective masters, prototypes and mold inserts after alloy, heat treatment and stability review.
Copper / brassDirect SPDT candidateCan provide good machinability and thermal behavior, but tool path, burr control and handling must be reviewed.
Ni-P plated substratePlated SPDT routePlating thickness, phosphorus content, hardness, adhesion and remaining stock must support the final optical cut.
Ferrous mold steelDo not assume direct SPDTDirect cutting is generally unsuitable because of rapid diamond tool wear. Consider compatible plating, ultra-precision milling, grinding or polishing.
Existing coated insertFeasibility reviewWe must confirm coating type, thickness, remaining allowance, damage history and whether the surface can be safely reworked.
Controlled process route

From drawing review to measured optical surface.

The final pass is only one part of the route. The pre-form, datum, environment, tool condition and inspection plan determine whether the generated surface can be trusted.

01Drawing reviewConfirm optical equation, effective aperture, center, edge, datum and acceptance requirements.
02Material routeSelect direct-turn substrate, Ni-P plating or an alternative machining route.
03Pre-form controlPrepare seating faces, datum diameters, stock and plating allowance before optical cutting.
04Machine stabilizationControl setup, spindle, tool position, environment and thermal equilibrium.
05Diamond turningUse rough and finish passes selected for material, form, feed-mark and edge requirements.
06Inspection feedbackVerify form, roughness, center region, edge condition and datum relationships.
What we control

Five details that decide whether the surface is truly usable.

Low roughness alone does not prove that a diamond-turned optical insert is ready for replication or assembly.

Center transition

The central region can reveal spindle, tool-setting or path problems that are not obvious elsewhere on the surface.

Feed-mark topology

Spacing and periodicity are reviewed because regular marks can influence reflection, scattering and appearance.

Edge and aperture boundary

Burrs, roll-off and overcut near the effective aperture can damage the usable optical area.

Plating integrity

The final optical pass depends on uniform, stable plating with sufficient remaining thickness and adhesion.

Datum-to-optical relationship

The optical surface must remain correctly located relative to the seating face, outer diameter, flange or assembly datum.

Repeatability between inserts

For replacement or multi-insert projects, matching the surface, datum and effective aperture is part of the machining plan.

Inspection and acceptance

Measure the function—not only the shine.

The inspection route is selected according to the drawing and the optical surface. Not every method is suitable for every geometry, coating or effective aperture.

Operator using a microscope-based inspection station at YISHUN
Microscope-based inspection is used for magnified review of optical surface details, edge condition and groove continuity where needed.
Form / profileInterferometry, profilometry or customer-specified comparison where the geometry and reflectivity allow.
Surface roughnessMeasured at agreed locations and directions; a single Ra value does not replace form or texture review.
Center and feed marksMicroscope or magnified visual review for center defects, periodic lines, scratches, digs and contamination.
Datum and dimensionsCMM or precision dimensional methods for seating surfaces, diameters, flange positions and assembly relationships.
Report boundaryMeasurement method, locations, sampling quantity and report format are confirmed before production.
Real production evidence

Moore Nanotech machine used for diamond turning.

Real Moore Nanotech diamond turning equipment at YISHUN
Real Moore Nanotech 250 UPL ultra-precision lathe used by YISHUN for single-point diamond turning.
YISHUN engineers reviewing a circular optical insert and drawing
Drawing and process review

Confirm geometry, material and the Moore diamond turning route before production.

A useful quotation should reflect the real geometry, substrate, coating and acceptance plan. Incomplete specifications often create more risk than the cutting operation itself.

2D and 3D dataSTEP, IGES, X_T, DWG, DXF, PDF or other agreed formats.
Optical definitionSurface equation, sag table, groove data or nominal profile.
Material and coatingSubstrate, hardness, heat treatment, plating type and thickness.
Effective apertureOptical zone, non-optical zone, center and edge boundary.
Acceptance valuesForm, roughness, dimensions, appearance and defect criteria.
Inspection planMethod, measurement positions, report format and sampling quantity.
Project quantityPrototype, validation insert, replacement insert or repeated production.
Existing problemCurrent tool marks, scratches, coating failure or replication issue.
FAQ

Questions buyers ask before selecting SPDT.

These answers define the project boundary before detailed drawing and process review.

Can you directly diamond turn hardened mold steel?

Usually not as a normal route. Ferrous materials cause rapid diamond tool wear. We may evaluate Ni-P plating or recommend ultra-precision milling, grinding and controlled polishing instead.

Does diamond turning eliminate polishing?

For suitable materials and applications, the optical surface may be generated directly. Additional polishing is not automatically beneficial and can change the profile or groove structure.

Can every freeform insert be diamond turned?

No. Rotationally symmetric and concentric geometry is the strongest fit. Non-rotational freeforms, deep sidewalls or blocked tool access may require five-axis machining or a combined route.

What causes visible rainbow or concentric marks?

Diamond-turned surfaces naturally contain periodic feed marks. Their spacing, height and optical effect depend on tool radius, feed, spindle behavior and surface requirements.

Can you rework an existing plated insert?

Possibly, but we must confirm the coating type, remaining thickness, damage depth, substrate condition and whether enough stock remains for correction.

Do you provide finished molded optical parts?

This page focuses on custom machining of optical mold inserts, masters and related tooling. Final molding or optical system design is not presented as the standard service scope.

Start with a process decision

Send the drawing before choosing diamond turning.

We will review geometry, substrate, plating, effective aperture, datum relationships and inspection requirements, then confirm whether SPDT or another ultra-precision route is more suitable.

Request Engineering Review

Start Your Project With A Free Quote

Our professionals are available to talk you through each of our offerings. We’ll be sure to answer you within 24 hours. Fill out the information below with as much detail as possible, and we’ll get back to you promptly.