Nov 2019 - 13: Citizen wraps-up swarf issue
Supplying quality conscious market sectors such as the automotive, aerospace, electronics and rail industries is why Cannock based Key Precision has put its faith in machine tools from Citizen.
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Down the years, the Staffordshire subcontract business has placed its stock in Citizen, installing three A32 sliding head turning centres in 20-13 and more recently adding an L32 Type 8 with LFV and an Iemca Boss 338-HD barfeed unit.
Like any other subcontract manufacturer operating in high-value supply chains, the ISO: 9001 and AS: 9100 accredited company has to have productivity and cost-down considerations at its core.
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This is why Key Precision specified the Citizen, as Greg Jackson told MTDCNC:
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\u201cThe machine is great, but the problem we now have is that we can\u2019t get enough bars on the L32.
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We have a particular component that we were making five at a time. W
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ith a few tweaks, we managed to get from 5 parts to 50 on an alternative machine, but now with the Citizen we\u2019re running 500-off lights-out without intervention.
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Now, the barfeed is running out of stock before we get a chance to re-stock the machine.\u201d
This is clearly a great problem to have for the subcontract business, as it was previously having issues with swarf wrapping and the necessity for an operator to remove string like swarf from the work envelope for machining to continue.
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By adopting the LFV technology, Key Precision can now run its parts lights-out massively increasing productivity.
Referring to the particular batch-production part that has been improved, Greg says: \u201cThe bearing retainer part is produced from 7075 aluminium with a 10 micron tolerance on the diameter all along the length.
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Originally we planned to have the parts ground, but the consistency of the Citizen and its LFV means we can eliminate that operation and drop finished parts out of the machine in a single hit.\u201d
\u201cWe are running the machine in non-guidebush mode with a stroke of 80mm; and using the full stroke, we can still comfortably hold tolerance and we can probably machine in the realms of 3XD.
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In addition, the LFV system is ensuring that the swarf is breaking off in very small chips, so we\u2019re not getting any damage on the part.\u201d
\u201cWe are now looking at different ways to get the bars off the machines, as in some cases, our collection system cannot contain the high-quantity and frequency of the parts.
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Additionally, we have to be careful not to damage any parts, especially on tight tolerance work.\u201d
Discussing the new Citizen L32 in general terms, Greg says: \u201cThe work envelope is very spacious for us to get into the machine and access tools and workpieces.
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Additionally, the door is very large, and the access is more comparable to that of a larger fixed head machine.
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There is also a back door to get to the tools from the rear.
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We have four driven tools at the front end with the option to put an arm in there for a manual B-axis, so we can go up to seven tools.
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We also have five live tools at the back and three deep hole drilling tools next to the sub-spindle.
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We have used this on quite a few occasions when you need extra-long drills that can go next to the sub-spindle, providing there are no clashes with the back-working tools \u2013 we have drilled over 180mm deep on the machine.\u201d
As well as the LFV system for swarf breaking, Key Precision specified the Citizen machine with medium pressure coolant supply.
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As Greg Jackson says: \u201cThis particular L32 model only has the LFV system on the main spindle, so we put medium pressure coolant supply on the machine with 80bar pressure. This enables us to clear any swarf from the back-working tools.\u201d