Choosing an Injection Mould for Parts with Tight Tolerances

When a plastic part has demanding dimensional requirements, compare mould proposals against the same drawing and ask each supplier to explain how critical features will be verified. Review the inspection process, trial plan, tooling materials, cavity layout, surface finish, and expected mould life together. Longterm’s custom precision injection mould service lists incoming quality checks, mould trials, dimensional inspection, and pre-shipment inspection, but project-specific tolerances and measurement equipment should be agreed before production.

What to Evaluate in a Mould Proposal

Begin by marking the drawing dimensions that matter most to fit, function, or assembly. Ask how these features will be measured, at what stage they will be checked, and how trial-part results will be documented against the drawing. A clear verification plan helps you compare suppliers on evidence rather than general assurances.

Next, check that the proposed tooling configuration suits both the part geometry and production needs. Longterm lists mould-base materials including S50C, P20, and 1.2738, and mould steels including H13 and 718H. Available configurations include single- and multi-cavity layouts, SPI or VDI surface finishes, and an optional hot runner. The stated mould-life range is 50,000 to 1,000,000 shots; confirm the expected life and operating assumptions for your specific design.

Inspection, Trials, and Supplier Experience

Inspection should be considered part of the technical proposal. The product information lists IQC incoming inspection, mould trial testing, dimensional checks, and full inspection before shipment. Longterm’s mould-service descriptions also refer to 3D inspection, full-dimension measurement, and sample confirmation. Ask the supplier to identify which checks apply to your project and what records you will receive. The published information does not specify tolerance values or measurement equipment, so these details need to be established for the part.

Longterm holds ISO 9001:2015 certification for its listed scope of precision mould design, manufacturing and sales, and plastic product sales. Its recorded projects include an electronic housing mould for a handheld device manufacturer in Italy and a double-shot overmoulding project for a consumer electronics shell in France. Reported customer feedback cited accurate dimensions and smooth surfaces in the first project, and good alignment with stable trial samples in the second.

Comparison Checklist

Frequently Asked Questions

What should I ask suppliers about dimensional inspection?

Request a list of drawing dimensions to be checked, the inspection stages, the measurement approach, and the format of the sample results. The listed checks include incoming inspection, mould trials, dimensional inspection, and inspection before shipment.

Are mould materials and finishes configurable?

The published choices include S50C, P20, or 1.2738 for the mould base; H13 or 718H for mould steel; and SPI or VDI finishes. Confirm the appropriate selection with the supplier against your part design and specifications.

What are the minimum order and lead time?

The product information states a minimum order of one mould set and a delivery estimate of 20–35 days. Other business information distinguishes lead times for simple and complex moulds, so request a schedule based on the final design and sample-approval requirements.

Making the Final Selection

Use one part drawing and one agreed inspection plan to compare mould options consistently. Consider material selection, cavity arrangement, finish, trial results, dimensional evidence, and mould life as related factors. Before committing, document any tolerances or measurement methods that have not yet been specified. Longterm provides custom mould making and development alongside plastic injection production, with after-sales technical support and maintenance guidance described in its product information. For technical enquiries, contact rogerluo@longterm-mold.com.

About Longterm

Longterm Manufacturing Solutions Limited was established in 2010 and serves international customers with mould design, tooling, precision machining, mould manufacturing, and parts production. The company lists a workforce of 50 employees and identifies North America, Europe, and Australia as key markets. Its cooperation examples cover consumer electronics, household appliances, and industrial parts, and it holds ISO 9001:2015 certification.