Drills provide productivity improvements

Posted on 10 Aug 2018 and read 919 times
Drills provide productivity improvementsIn 2016, when Surrey-based GPR Ltd added five-axis working — a Matsuura MX-520 — to its three-axis machining capability and won a contract to machine Hookes joints for earthquake simulation tables, the company turned to the cutting-tool manufacturer Industrial Tooling Corporation Ltd (ITC), Tamworth (www.itc-ltd.co.uk), for help in specifying and supplying the optimal tooling solution for the new machine.

ITC fully tooled the Matsuura with a comprehensive range of tooling that included Widia M200 indexable shell mills, BIG Kaiser BBT40 tool-holders with face-mill adaptors, BIG Kaiser HMC milling chucks, Widia 5777-series solid-carbide end mills, standard- and extended-length Widia VariMill 2 end mills with Widia HPV shrink-fit tool-holders, seven-flute VariMill 3-series tools and 47N0-series ball-nose tools.

ITC currently supplies more than 50% of GPR’s cutting tools, so when the company recently won an order to manufacture aluminium telecommunication parts and found that it was suffering poor tool life during drilling cycles, GPR once again called in ITC technical sales engineer Dave Cleeve.

GPR managing director Vernon Ward said: “We won an initial order for 20 sets of mobile-phone test-bed housings, with each set comprising six parts that included four centre guides.

Each of these required the drilling of over 50 holes of varying diameters — 2.1, 2.5, 3, 4.2 and 6.2mm.

"There were more than 300 holes per set, and we were averaging three drill failures on each. The roughing, pocketing, slotting and other operations were all very productive, as we were using ITC’s aluminium end mills, but the drilling cycles were letting us down.

“We persevered with the HSS drills we had been using, but when the order was extended to include another 80 sets of housings requiring over 24,000 drilled holes, we called ITC’s Mr Cleeve for a solution.

"We knew we couldn’t meet the tight delivery schedule with drill failures.”

Mr Cleeve suggested using Widia’s VDS solid-carbide through-coolant drills to eliminate tool failures — with their associated downtime and costs — and improve the cycle times.

With HSS drills, each of the four centre guides had an overall cycle time of 70min; using Widia VDS drills immediately cut the cycle time to 49min.

Eliminating 'pecking'

This 20min reduction per part is attributable to a number of factors, including: the elimination of tool burnout and subsequent tool change-overs; the ability to run the VDS drills at higher speeds and feeds; and the ability to feed the drill straight through the part without the need for ‘pecking’ (the VDS drills’ through-coolant feature eliminated pecking cycles by flushing the swarf away from the cutting area, while also keeping the cutting edge at its optimal operating temperature).

Mr Ward said: “We completed the entire batch of 80 sets with their 24,000 holes using a single set of drills; and at the end, the VDS drills were still in an ‘as new’ condition.

“They may have cost more than our previous drills, but they paid for themselves by the time we had machined 20 parts.”

Following the success of the VDS drills on the aluminium components, GPR enquired about drilling holes in Duplex (a grade of stainless steel that is commonplace in the oil and gas industry) when it won an order for drilling oil-well monitoring equipment.

ITC again recommended the VDS range for drilling a batch of 10 Duplex bars that required four 10mm-deep holes per part; with a pre-drilling and drilling cycle, the total drilling time was 4min 58sec per part.

After completing this first batch, GPR won an order for another 130 parts. Wanting to reduce this cycle time while using a Haas Mini Mill instead of the Matsuura, GPR again asked ITC’s Mr Cleeve for his suggestions.

He recommended 3xD VDS drills in 3.2mm and 4mm diameters; and unlike the through-coolant solid-carbide drills used on the Matsuura, the drills used on the Mini Mill were used with flood coolant — and still reduced the cycle time from almost 5min to just 44sec.

Mr Ward said: “While the payback period on the drills is certainly impressive, what has overwhelmed us is the tool life, along with the flexibility to drill anything from aluminium to Duplex — and probably many more material types.

"The Widia VDS drills have slashed cycle times, improved hole quality and finish — and given us tools that we are confident to run for long periods without having to continually check tool wear and performance.”

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Garrick Ridgway Engineering Ltd