How Precision Mold Base Accuracy Is Machined and Verified
Accuracy comes from the sequence, not one machine
Plate accuracy is decided well before the finishing pass begins. Our workflow rough-machines datum faces first so that every later operation shares the same references, then leaves material in place so internal stress in the steel can relax before final finishing. Skipping that relaxation stage is the usual reason an otherwise accurate plate drifts after delivery: machining released internal stress unevenly, and the plate quietly keeps moving once it is bolted up in the customer's toolroom rather than on our inspection table.
Finishing then runs in a constant-temperature workshop, because a large steel plate expands measurably with shop temperature and a dimension taken early in the morning is not the same measurement taken in the afternoon. Inspection is set at three control points - after roughing, after finishing and after assembly - so an out-of-tolerance feature is caught at the operation that created it rather than at final fit-up, when the remedy is usually a new plate rather than a few minutes of extra machining time.
Matching the tolerance to the operation
Capability is quoted per process, because machines differ in both travel and precision. Gantry machining centres hold ±0.01 mm over a 2500 by 1600 mm table for large plate faces and cavity roughing; vertical machining centres hold ±0.005 mm within 1200 by 600 mm for guide pillar holes, counterbores and hole patterns; jig grinding reaches ±0.001 mm for high-precision bushing bores; and large surface grinding holds ±0.002 mm across 2000 by 800 mm for flatness and parallelism between opposing plate faces.
Over-specifying tolerance is expensive and rarely necessary. A blank plate face does not need the tolerance of a guide pillar bore, yet a blanket note on the drawing forces the tight process across every feature and adds time to every plate in the set. Mark which dimensions are genuinely critical to assembly and fit. Our machining envelope extends to 2000 by 1300 by 800 mm, and plates beyond that size can be machined in sections and assembled, which we confirm during drawing review rather than assuming.
What you receive with the plates
Final verification uses a coordinate measuring machine rated at ±0.0015 mm within a 1200 by 800 mm measuring envelope, checking hole coordinates, hole pitch, perpendicularity and flatness across the plate faces. Measurement data ships with the goods, so any dimensional question is settled before your toolroom starts assembly, backed by a written record rather than a recollection of what was agreed on the telephone weeks earlier. Guide pillar perpendicularity and bushing hole pitch are recorded feature by feature, because those are the dimensions most likely to cause binding once assembly begins.
Material traceability sits alongside that data. Mould steel arrives by batch with mill certificates and hardness checks recorded before production begins, so a batch that fails incoming inspection never reaches a machine tool, and every finished plate can be traced back to its melt. Plates then receive rust-preventive treatment and reinforced packing before dispatch. Tell us at drawing stage which dimensions must appear in the report and we build the inspection plan around exactly those features, rather than reporting everything indiscriminately.
FAQ
What tolerances can you hold?
Conventional machining is quoted at ±0.01 mm, finishing at ±0.005 mm and jig grinding at ±0.001 mm, subject to structure and process. Holding the tight end depends heavily on plate size and geometry, which is why we confirm the achievable scheme during drawing review instead of promising it in advance.
How large a plate can you machine?
The maximum machining envelope is 2000 by 1300 by 800 mm, and plates beyond that can be machined in sections and assembled. Large surface grinding runs to 2000 by 800 mm; give us plate dimensions at enquiry so the correct machine is scheduled.
Do inspection reports come with the shipment?
Yes. Key dimensions are measured and the CMM data accompanies the goods together with the material certificate for the batch. Please state which features need reporting on the drawing so the inspection plan covers exactly those.
All figures above refer to standard product data sheets; final confirmation is subject to written quotation.