Speed increases capacity

Good quality machine tools operate reliably and hold tolerance for two decades or more. The problem is that technology moves ahead so fast over such an extended period that the productivity of older machines cannot match that of their newer counterparts.

This was the situation Redruth subcontractor DP Engineering found itself in until it purchased three new Cincom lathes from Citizen Machinery UK. They are an L20-XLFV installed three years ago, an identical machine that arrived in autumn 2021 and an M32-VIIILFV bought at the end of last year. The latter two machines were direct replacements for equivalent 20 mm and 32 mm capacity sliders of similar type and make bought around the turn of the millennium, several machine generations ago.

Philip Anthony, DP Engineering’s Sales and Marketing Director commented, “The faster rapid traverses and higher power and speed of the main and sub spindles as well as of the driven tools on the new lathes have increased our capacity considerably. One stainless steel aerospace part we previously turn-milled in one hit on an L20 that is 20-plus years old now takes half that time to produce on its modern replacement.

“It is a similar story on the 32 mm machine, which is more user-friendly than the former generation lathe and has better access and visibility into the machining area. Moreover, the addition of a rotary B-axis on the gang tool post enables us to machine more complex parts than was previously possible on our sliders.”

A notable technological advance from Citizen since DP Engineering purchased the earlier Cincoms was the introduction five years ago of its proprietary LFV (low frequency vibration) chip breaking software running in the Mitsubishi control. It has resulted in a significant increase in productivity when machining malleable materials such as titanium and stainless steel.

It is particularly beneficial for the subcontractor, as one-third of its turnover is derived from the aerospace sector in which the use of such materials is commonplace, as it is in the medical industry, which has also generated more work since the start of the pandemic. Normally during machining, stringy swarf often entangles itself around the tool and component, risking damage to both and necessitating lathe stoppage to clear it from the machining area.

Mr Anthony explained, “The first L20 we bought in 2019 has LFV. We knew about the technology and sent a team of engineers to Citizen Machinery’s Brierley Hill centre to see demonstrations of the chip breaking function in action.

“For certain parts of cycles, it is very effective at ensuring that what usually becomes a bird’s nest of swarf is broken up into shorter chips, avoiding having to stop the machine to remove it and the consequent loss of production.

“The best part is that LFV can be programmed to stop during a cycle when it is not needed by inserting a G-code, minimising the slight reduction in metal removal rate during the periods when the tool oscillates away from the component’s surface to break the chips.

“On some jobs, even when cutting stainless steel, we don’t have to use LFV at all. It depends on the component design, the tolerances that have to be held and the tooling used. However, it is fantastic to have it there for when we need it.”