Plastics and Polymers Editing and Proofreading Services

A drawing arrives with ±0.05 mm on a 180 mm dimension across a moulded part. The designer put it there because that is what the assembly needs. The moulder looks at it and knows that this material, in this wall thickness, with this gate position, will move more than that between a Monday morning start-up and a Friday afternoon, whatever the tool does. Somebody has to have that conversation, and it is much cheaper as a document than as an argument about rejects.

We edit what moulders, extruders and polymer processors produce — part tolerance and capability documentation, design for manufacture guidance for customers, material datasheets and design value documentation, tooling specifications and cavity documentation, process capability studies and reports, shrinkage and dimensional stability documentation, quotation and technical feasibility responses, first article and dimensional reporting, colour, appearance and finish specifications, and secondary operation and assembly specifications. Our editors work on the conversation between a drawing and a process.

The tolerance and capability document is where a moulder either sets expectations or accepts an impossible drawing, and its failure is answering the drawing rather than the requirement. A moulder who quotes to a tolerance they cannot hold has bought a rejection problem, and one who simply refuses has lost the job. We work through these so each dimension on the drawing is answered with what the process can actually achieve, expressed as a capability figure over a stated number of shots and conditions, since a single measured part proves nothing about a process; so the reason a tolerance is difficult is explained in terms the designer can act on — wall thickness variation, gate position, the shrinkage direction relative to the dimension, the parting line — because a designer told that a dimension is difficult can often move it, and one told it is impossible cannot; so the alternative is offered, whether a datum change, a dimension taken from a different feature, or a secondary operation with its cost; so the conditions the capability depends on are stated, including material lot variation, colour and regrind content, given that a capability achieved on virgin natural material is not the capability on 20% regrind in black; so the dimensions that will drift over the tool's life are named with when they will need attention; and so the drawing's critical dimensions are agreed as a short list rather than all of them being treated equally. Documents written this way turn an argument into a design change.

Everything you send is treated in confidence, including drawings, process data and customer information. We are editors rather than polymer or tooling engineers, and we offer no view on materials, tolerances or process capability. What we can do is make the conversation happen before the tool is cut.