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Product category: Vertical machining centres (VMC)
News Release from: 600 Centre | Subject: Bridgeport Mouldmaster VMC 1000 XP
Edited by the Manufacturingtalk Editorial Team on 30 March 2001

Mouldmaker cuts hard metal die parts

Howard Engineering, a specialist in pressure die and injection mould tools has recently completed an GBP800,000 contract to produce a suite of 47 mould tools for a multi-national company.

Howard Engineering, a specialist in pressure die and injection mould tools has recently completed an GBP800,000 contract to produce a suite of 47 mould tools for a multi-national company Key in the manufacture of the tools, using hard metal machining techniques, was a recently installed Bridgeport Mouldmaster VMC 1000 XP vertical machining centre supplied by 600 Centre of Shepshed near Loughborough

The Bridgeport machine is used to cut both pressure dies and mould inserts as well as copper and graphite electrodes.

Says Graham Howard Managing Director: "For cutting hard metal, the Bridgeport is an excellent machine but most important to us is its capability to act as an all-round machining centre." He follows on to say: "We are now able to cut P20 and fully hardened HRC 46-54 die steels which gives us a big advantage in the case of aluminium pressure die inserts.

Generally these inserts would tend to last for approximately 150,000 shots, when made using an EDM process method but when cut from hardened steel, last considerably longer." Following the completion of the compressed air fittings tooling, Graham Howard reflects a huge improvement in as machined surface finish.

"While we benefit from higher speeds and feeds since the machine was installed, hand finishing has been cut by half from typically two days for a complex tool, down to less than one.

These are significant savings," he maintains.

Formed in 1986 by Graham Howard based on his experience gleaned from operating the toolroom for his father's precision engraving business and his formal apprenticeship background, Howard Engineering now employs 38 people working to GTMA world class standards.

Repeat business is important with the majority of customers coming back time and time again which means a core of 15 companies takes up around 90 per cent of available capacity at the Birmingham factory.

Almost half the orders are related in some way to the automotive industry.

Graham Howard explains how most of his business has become working partnerships with both parties exchanging information.

"This helps us to understand the function of what we are producing.

In turn, we can help with tool and component design information which can save them material, moulding time or even increasing the life of the tool or component in service," he says.

For the past decade, Howard Engineering has been investing in the latest technology which is helping to keep it at the forefront of its niche market.

Originally Graham Howard targeted injection moulders by producing high quality mould tools and pressure dies but has progressively developed a specialisation in pressure dies for zinc, aluminium and magnesium.

Also injection mould tools for plastics are produced with the capability to make a complete tool up to 5,000 kg and some 1,000 mm square.

Careful purchase of a variety of prismatic machines, grinders and die sinkers means both types of tools can be produced as Graham Howard outlines: "It's more or less the same thing, you either squirt hot metal or hot plastic into the tool.

However, there are totally different knowledge and skill bases needed for the tool construction.

With the flow of the material being so different and the increased pressure required, an injection tool may be placed on a 500 tonne machine, while an aluminium pressure tool is more likely to be installed on a 1,200 tonne machine." He follows on to say how a pressure die will need to be roughly twice as big as an injection mould tool and an injection mould tool will literally do millions of components if it is made correctly.

However, a good pressure metal tool will often only yield 150,000 parts because the process can be brutal on the tool.

"The heating and cooling ways are common to both types of tooling and we have our own deep hole drilling machine to generate these," he explains.

Tool design is a strong feature of Howard Engineering's capabilities, with four in-house designers using the company's CAD system.

A variety of software is used to cover the different files sent in by various customers, including AutoCAD, PSDraft and Mechanical Desktop 4.

Graham Howard explains: "The job often dictates which system we use, but we prefer to use surfaces for complex jobs." He then explains the trouble he finds with solid models is the absence of tolerances.

"The CAD design may put tapers and drafts on, but there are no upper and lower limits and often no indication of the critical features and dimensions," he says.

"They assume a perfect world, but unfortunately castings and mouldings vary substantially with shrinkage.

As such, we often have to make tools with 'metal on', that way we can fine tune the tool to produce the component as designed." The compressed air fittings project required the tooling machined to mean tolerance on the new Bridgeport.

Says Graham Howard: "We are not at the forefront of high speed machining at present, but the Bridgeport Mouldmaster offered us a good, solid intermediate step.

There are a lot of machines available, some at double the price.

But we reckon for what you pay twice as much for, you will probably only get 10 per cent performance improvement, which is a high price to pay." He also explains how they looked carefully at the servicing and maintenance support.

"If things do go wrong, we know we can get some fast support because spare parts are made just up the road in Leicester.

We also considered the importance of a robust spindle.

You can get faster machines but we did not want to be buying a new spindle every few months," he maintains.

So overall, a key element in the decision making was the 600 Centre's excellent reputation and the inclusive package they were able to put together.

"They proved to us that they have the training and servicing back-up that we require and the machine's maintenance is also included as part of the package," he says.

Controlled by Heidenhain TNC 426, the Bridgeport falls into line with the company's other CNC machines which feature Heidenhain control systems.

Only simple parts and skim cuts to relieve the 'metal on' condition of a tool for shrinkage allowance are programmed at the machine while the other programs are created off-line and DNC downloaded.

Phillip Howard, the founder's son, looks after the tooling and cutting strategies used on the Bridgeport, he says: "Now it is a case of keeping up with cutter technology and strategies which make a big difference to the efficiency of the machine tool." Although most of the company's work is three axis machining it varies widely in complexity.

"We have had to re-educate ourselves for hard metal machining, and we plan to try different strategies depending upon the shape of the tool." He explains how they use mainly Hitachi cutting tools held in Anniversary chucks from Nikken: "These are balanced as supplied to 20,000 revs/min and I'd say, are as good as heat shrink tooling for our work." While mould and die work predominates the business, Graham Howard is proud of his Royal Mint customer which uses his engraving operations.

Here, coining dies are produced for Ministry of Defence medals and those people that manage to complete famous sporting events such as the London Marathon probably have a commemorative award produced by one of Graham Howard's dies.

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