KMF Precision Sheetmetal Ltd — the UK’s largest sheet-metal sub-contractor, with 420 staff and a turnover of £32 million — manufactures components for a diverse range of products, including premium-class aircraft seating, coffee-vending machines and electrical distribution boards. The company says specialist CAM software is vital for nesting a range of parts for several customers on the same sheet.

Operating from a 120,000sq ft facility in Staffordshire, KMF ships around a million piece parts every month. Programming manager Stephen Gardener says the Radnest function within the company’s Radan sheet-metal CAD/CAM system from Vero Software (www.radan.com) saves time and reduces waste. “It plays a large part in our day-to-day business, and we use it in two different ways.

“Firstly, it allows us to consolidate large assemblies where we want to produce an exact quantity of parts to match the bill of materials.

A number of our assembly jobs consist of 100 or more parts, and the project nesting function means we can nest different materials and thicknesses on different-size sheets. These would typically be saved as a project, with all nests saved under one job number.

“Secondly, Radnest allows us to nest small batch quantities. If a customer wants five off, we can nest them on sheets with components for other customers. However, if we had to run a full-sheet program for just five parts, it could leave us with about 20% waste.

“As our batch sizes can vary from one off to thousands off, we have a full-time nesting office analysing all jobs to see if the individual quantities justify running their own nest program. If they don’t, the parts will be separated and nested with parts for other customers. This way, we can maximise sheet utilisation for any batch quantity.”

KMF has used Radan for a number of years to drive its range of Trumpf punch presses, combination punch/laser machines and lasers. However, a manual press brake operation for the bending process caused a considerable bottle-
neck, with a typical set-up taking around 45min.

Halving set-up timesMr Gardener says investing in Radan’s specialist Radbend module for programming press brakes has more than halved set-up times. Radbend also means KMF can usually set up a job using just one part, saving four or five try-out parts.

“Radbend also minimises waste by simulating the full bending sequence before starting to fold metal. Operators simply call up the program and view it in 3-D on their machine console.”

KMF currently runs Radraft, Radan 3D, Radprofile and Radpunch on a number of Trumpf machine tools, all fed by Stopa tower systems; two of them also feature a ShearMaster for cutting sheet ‘skeletons’.

KMF’s process with Radan begins by importing the 3-D component data, then determining the material properties and producing a flat development with bend allowance; this is sent straight to the profiling or tooling stage.

“At this point, we can use Radraft to alter any details or features before considering the tooling, and then select either laser profiling or punching. Nesting ensures best sheet utilisation, and Radbend produces programs for the press brakes — either straight from the model or via Radraft’s ‘fold from flat’ feature.

“All this combines to give us full-sheet nesting, plus CNC punching, laser and press brake programs all ready to be downloaded to each specific machine from the server, maximising each machine’s capabilities and allowing us
to produce all our metalwork to the tightest possible tolerances.”

Operations director Keith Nichol says a typical contract starts with the customer’s order being loaded onto the Vero system, then taking its routing either through the design process or the engineering planning process to give a method of manufacture and bill of materials, which are then translated into manufacturing requirements.

“Radan provides everything we need to convert the design into machinable parts for the punches, lasers and press brakes, giving us accuracy and repeatability. Lead times are typically between seven and 14 days, depending
on the complexity of the products.”

He says Radan also plays a key role in KMF’s apprenticeship programme. “Apprentices are an important part of the company’s future, as they gain skills in all parts of our operation. We have a Radan training licence and a CNC machine in the apprentice workshop, which is vital in helping them understand how to develop sheet-metal parts with Radan — and how it programs CNC machine tools.”