In 2007, Tridan Engineering Ltd made the decision to reduce its emphasis on commercial, agricultural and power generation sub-contract machining and focus on prestigious aerospace contracts, and the Clacton-on-Sea company has made significant investments in infrastructure, accreditations and machine tools to help it achieve this goal.

In the last two years, AS9100-certified Tridan has spent more than £2.5 million, with new acquisitions including two Mazak Variaxis i-500s, an i-600, an i-700, a Mazak Quickturn 300, a Quickturn 200MSY, and a six-station Palletech automation system; the company also has also ordered three machines from XYZ.

The investment in high-specification machines — including four- and five-axis machining centres — combined with the processing of an increasing variety of materials, prompted Tridan to review its supply of cutting tools.

In the two years since initiating this review, the company has reduced the number of its cutting-tool suppliers from 14 to just two, and Tamworth-based Industrial Tooling Corporation Ltd (ITC — www.itc-ltd.co.uk) is one of them.

Tridan’s senior production engineer, Peter Townsend, said: “When it came to cutting tools, we had no consistency or standardisation, with our shopfloor staff ordering new tools from one of our suppliers as and when they needed them.

“To consolidate our suppliers, we first eliminated a few of the smaller vendors, then started 18 months of trials with many of the internationally recognised tooling brands.

“We were looking for a complete package, not simply comparing one vendor with another based on the usual parameters of tool life, performance and cost reductions — although these were still key considerations.

“We were reviewing the service and technical support, the rapport between our engineers and the tooling representative, as well as the diversity of the product portfolio.

“However, it was the installation of twin-pallet and six-station machining centres designed for extended periods of ‘lights out’ running that highlighted the importance of consistent machining performance and tool reliability.

“During the trial period, ITC was fast emerging as the front runner to win our solid-carbide round-tooling business, thanks to the relationship between Gary Bambrick — ITC’s technical sales engineer — and our machinists; and with tooling manufactured in Tamworth, the rapid turnround on standard and special tools was important.

“The benefits of ITC’s involvement were apparent with the manufacture of aluminium frame racks for the aerospace industry; these are machined in batches of 10-off every couple of weeks and require a significant amount of material removal.

“Mr Bambrick recommended that we use ITC 49G9 Series ripper end mills with through coolant and a trochoidal machining strategy; that immediately reduced the cycle time from 6hr to less than 5hr.”

Machining thin walls

These racks feature a number of machined thin-wall sections, but the cutting forces resulting from the tools pushing against the thin walls gave an inconsistent wall thickness and a wavy finish.

Mr Bambrick worked closely with Tridan and ITC’s Tamworth headquarters to change the geometry, edge preparation and corner radius on a 10mm-diameter 3081 Series end mill that was used for finishing the thin wall profiles.

Mr Townsend said: “This cutter not only resolved that specific technical issue but also highlighted the level of expertise and support available from ITC.”

With the six-station Palletech system on its latest Mazak machining centre, Tridan is achieving more than 140hr of production every week.

Manufacturing titanium alloy enclosures for the aerospace sector, the machine has been producing 50 parts per week with a cycle time close to 3hr per part; and by using ITC’s VariMill end mill, each cutter is achieving four days’ tool life. When Mr Bambrick suggested trying a diamond-coated end mill, tool life went up to seven days.

Another application that was causing Tridan difficulties was a titanium nose cone for the defence industry. This had a rough-machining cycle time of 45min; ITC was able to cut that to 25min with a five-fluted ripper cutter — a significant saving on a batch of 100 parts.

Following internal rough machining, the cone requires a series of slots and features to be machined and the extended reach necessary to access inside the cone had been causing vibration that impacted tool life.

Mr Townsend said: “The combination of the challenging material and the extended reach requirement meant that the resulting vibration was ruining cutters. Furthermore, the slots have a 0.03mm tolerance, but we had been struggling to hit this tolerance because of the vibration.

“ITC developed a 2.8mm-diameter extra-long end mill on a 12mm-diameter shank that instantly eradicated vibration, resulting in improved surface finish and tool life — the latter going from one tool for every three parts to five tools for the full batch of 100 parts.

“Meanwhile, following the success of a VariMill 477, we trialled the same roughing tool on a chassis part manufactured from S154 hardened steel for the defence sector.

“We had been using a high-feed indexable end mill from another supplier, and we were burning out two or three insert edges on each part. The cycle time was 12hr per part, and the parts were machined in batches of 30.

“With the VariMill cutter, we cut the cycle time from 12hr to just three — and managed to complete a full batch with just two end mills.”