Aerospace Manufacturing hears how a turned parts subcontractor is raising its production efficiency with technology from Citizen Machinery UK.

Founded in 1965, subcontract machining firm Apel specialises in the manufacture of precision components for the aerospace industry. The company began investing in Citizen CNC turning centres in the 1980s to help raise efficiency and over time has continued to re-invest in modern, highly productive lathes purchased exclusively from Citizen Machinery UK.

Today, Apel operates nine Cincom sliding-head lathes and one Miyano fixed head model. Together they produce around 50,000 components per month across more than 3,000 part numbers. Utilisation of these Citizen CNC lathes, and related technologies has led to much increased levels of productivity and profitability.

The technology that has contributed most to raising efficiency of production at Apel is Citizen's proprietary low frequency vibration (LFV) chip breaking software, which is part of the operating system in the control of three of the six 20mm capacity Cincom L20s on site. When activated, the function breaks what would otherwise be long, stringy swarf into short, manageable chips. Around 50% of material processed by Apel is aerospace grade stainless steel bar and LFV is especially effective when processing this alloy.

“We were an early adopter of LFV in 2018 following a visit to Citizen Machinery's technical centre to witness demonstrations,” begins Apel's quality director, Paul Bowker. “The function reduces metal removal rate slightly, so we don't use it all the time, but it's really useful to be able to pick and choose when to program the function to start and stop.

"We switch it on mainly when turning stainless steel components on the LFV-equipped machines, especially when processing parts shorter than one inch. It is normally chip breaking the metal for up to half of a typical cutting cycle."

He further explains that the decision to use LFV is also based on the surface finish required on components. Some customers' drawings stipulate a very high surface tolerance and machining with the LFV function switched on allows this to be achieved by turning alone, avoiding the need to centreless grind parts afterwards, thereby reducing unit manufacturing cost and raising profitability. Dimensional and surface finish tolerances on many component drawings can be met and maintained when using this facility.

Apel also uses Citizen Machinery's adaptive guide bush (AGB) system, which automatically compensates for variation in bar diameter, preventing stock seizing in the bush. It also constantly maintains concentricity to prevent run-out. Downtime is avoided and tight machining tolerances are maintained. The system is used not only on the 20mm capacity sliding-head lathes but also on three 32mm capacity Cincom models on the shopfloor.

The AGB systems ensure reliability during unattended operation by compensating for bar diameter inconsistency and preventing stoppages. Additionally, the LFV machines do not have swarf clogging the working area when processing stainless steel. It contributes further to reliability and eliminates the need for an operator to be in attendance to untangle ribbons from the components and tooling.

Bowker concludes: “Our nine Cincoms, as well as the Miyano for turn-milling larger components up to 50mm diameter, support all of our production and will continue to do so as we increase our volume of work in the expanding global aerospace industry.”

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