Machining costs flattened at Gardner Aerospace

As one of Europe’s largest manufacturers of aerospace components, Gardner Aerospace places huge levels of pride in its precision, quality and cost-efficient streamlined manufacturing. It is for these reasons that the company, which has manufacturing facilities around the globe, has opted for cutting-tool support from MSC Industrial Supply Co.

At the Broughton manufacturing site in north Wales, Gardner Aerospace manufactures structural components for aerospace OEMs from a variety of material types. To ensure the most efficient production method, and that a cost-effective solution is integrated into the business, the Broughton facility has in the past 12 months instigated a working relationship with MSC. The introduction of MSC regional applications engineer Stuart Wiezniak to Gardner Aerospace was a decision based upon trust and reputation, with Wiezniak already yielding impressive results for the company at its Hull manufacturing facility.
The new working relationship almost instantly yielded several cost savings and productivity gains as soon as he entered the Broughton site. With MSC’s decades of industry expertise, Wiezniak was recently introduced to a troublesome component that, with an annual production output quantity of 7920, was tying up a turning centre for much of its daily three-shift operation.

The S98 stainless rod-end component with a 30 mm diameter sphere required a considerable material removal rate (MRR) to create a flat on each side in a cost-effective cycle time. However, using the turning centre, the limited rigidity of the Y-axis milling head and the three-jaw chuck clamping set-up created frequent machine alarms and stopped production. To eliminate this error, free-up machine availability, reduce cycle times and cut tooling costs, Wiezniak worked with Gardner to move the process to a Dah Lih four-axis machining centre with a BT40 spindle taper, in the process helping develop a fixture that can hold five parts in a single set-up. The results are reported to be little short of staggering.

The previous set up on the turning centre utilised a 16 mm diameter ball-nose end mill with two indexable inserts, each featuring two cutting edges. This end mill, supplied by one of the world’s leading cutting-tool manufacturers, ran at 3 mm depths of cut with a paltry MRR of 6.64 cm3/min and a feed rate of 246 mm/min. By recommending an alternate machine, a different work-holding configuration and more applicable cutting tools, Gardner Aerospace is now saving more than £37,500 per annum on this one job – and there is scope to bring about an even larger cost saving.

By designing and manufacturing a fixture to clamp and machine five parts simultaneously, and then having the insight to utilise the 4th-axis to rotate the components 180° to generate the flat on the opposite side of the sphere, Gardner is realising massive productivity gains. MSC has been integral in this process and in subsequently reducing manual intervention, increasing productivity and cutting costs.

From a tooling perspective, Wiezniak removed the previous indexable ball-nosed tool and replaced it with a Dormer Pramet 32 mm diameter high-feed end mill featuring five inserts (four edges per insert). Applying inserts with Dormer’s M6330 coating grade, the MSC expert increased the machining parameters beyond recognition. Running the new rough and semi-finish end mill at a 0.7 mm depth of cut and a cutting speed of 180 m/min, MRR leapt from 6.64 cm3/min to more than 50 cm3/min. This outcome reduced the cycle time from 5 minutes 49 seconds per part, to just over 33 seconds.

The strategy applied by Wiezniak utilises the Dormer end mill for the semi-finish process, completing the task with a larger 50 mm diameter button tool. Taking 26 seconds of rough machining with the Dormer end mill and a 7-second cycle with the finishing tool, the total 33-second cycle yields Gardner Aerospace a reduction of more than 5 minutes per part, a significant saving considering the annual quantities required.

Commenting upon the strategy, Wiezniak says: “The first challenge was to ensure machine availability to move the part from the turning centre to a machining centre. From there, we had the freedom to instigate process changes such as the five-part fixture for machining. Devising a platform for rigid machining was the foundation block and, once this was in place, we could look more closely at tooling strategies and subsequent savings.

“The beauty of creating partnerships with MSC is that we have access to hundreds of vendors and more than 120,000 product lines, so we’re not constrained by a single-source tooling supply,” he continues. “As a result, we can ensure the best tool for the application. In this specific application, the Dormer Pramet 32 mm high-feed end mill was the optimal choice for high MRR. For the finishing cycle, the rod-end parts require an 8 mm radius on the flats, so we opted for a 50 mm button tool with four inserts, each with four cutting edges. Running at a feed rate of 622 mm/min with a single finishing pass of 0.1 mm depth of cut, the button tool delivers outstanding surface finishes with tool life of 400 parts per cutting edge.”

Summarising on the savings that have been made on the rod-end parts, Wiezniak says: “Cutting-tool strategies are always a balance of costs versus productivity rates. In this instance, the annual tooling cost increased by £321 per annum to £2678, but we have slashed machine hours by 81% from 724 hours to 141, while the cost per part has reduced from £28 to £23. The saving of £37,542 not only absorbs the slight increase in tooling costs, but improves process reliability, frees-up machine capacity and
man-hours, and enhances component quality. We have exceeded customer expectations with regards to meeting the original objective, while delivering the project goals on-time.”

Referring back to the “equally large cost reduction potential” on this job, Wiezniak adds: “The rod-end parts has two different part families within the 8000 quantity requirement. Some parts require a 24.8 mm diameter bore on the machined flat, while other parts need a 17.46 mm diameter bore. Before the COVID-19 pandemic and subsequent lockdown, we investigated the possible options, trialled several tools and the results already look impressive. However, although we can expect another huge leap in cost savings, we’ve not yet had the opportunity for final approval with these tools. When the opportunity arises, I’ll be certain to deliver even more fantastic results for Gardner Aerospace.”

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