Route to increased productivity at CTPE

Move to five-axis high-speed machining brings further benefits for sub-contractor

Posted on 04 Mar 2018 and read 1166 times
Route to increased productivity at CTPEEven after extending its day shift, Suffolk-based CTPE was still having difficulty producing aluminium covers for a
medical housing quickly enough after the customer raised the call-off rate to 100 per week.

The company was producing these parts in two operations on an ageing 40-taper three-axis machining centre.

A new production route proposed by Kenilworth-based Whitehouse Machine Tools Ltd (www.wmtcnc.com) was based on using a Japanese-built 30-taper machining centre from Brother.

While also a three-axis model, this was deemed capable of halving the cycle time and eliminating CTPE’s capacity problem. A Brother S700X1 was installed in August 2016.

Whitehouse edited the existing part program; and although the part was still produced in two operations, the cycle time was indeed reduced by 50% — to one hour.

The time saving is mainly due to a four-times-faster tool change at 1.4sec, a 16,000rev /min spindle with through-coolant rather than the 6,000rev/min of the previous machine, four-times-faster axis acceleration (2g) to a rapid-traverse rate of 50m/min instead of 18m/min, and the fact that the part program runs so much faster in the latest Brother C00 CNC system.

W2Since the machine was installed, CTPE has further optimised the program to machine six parts on the table with 14 tools; the company is also using new types of cutters.

The effect has been to reduce the cycle time per part to just 30% of the original.

Another example of the savings that have been achieved relates to an aluminium flow housing for a customer in the scientific sector.

Previously produced in three operations on a three-axis machine in 15min, this part is now produced in two operations on an S700X1 in 6min — a 60% time reduction.

Alex Taylor, who runs CTPE in Mildenhall with his father Chris, said: “It was our first machine from Brother — and also our first with a 30-taper spindle.

“We were impressed by the quality, compact footprint and speed of the Japanese machine when we saw it in Kenilworth, and comments about Brother — both on-line and by word-of-mouth — were complimentary.

“After the S700X1 was installed, we were able to get almost two weeks ahead on the medical-cover job; previously, we were always struggling to keep up with the current week’s production.”

Five-axis benefits


Such was the success of the project that when a second multi-national company in the medical sector — a long-standing CTPE customer — asked for a new family of 6061 aluminium parts to be produced, Chris and Alex Taylor had no hesitation returning to Whitehouse for another S700X1, this time fitted with a two-axis Nikken table.

It was installed in June last year and replaced another three-axis vertical machining centre.

The parts were being machined in the USA, but the customer — a Germany-based OEM — wanted a single source of supply and was confident of CTPE’s capabilities.

Six components are required, half of which are suited to three-axis machining while the others benefit from five-face machining in two operations using 3+2-axis cycles (they would otherwise they would need eight set-ups on a three-axis machine).

Chris Taylor said: “We like the three-axis Brother and two-axis Nikken combination, as we can mount the compound table on one side, leaving the rest of the machine table free for fixturing a second component in a vice for three-axis machining.

“This approach means we can get two-operation components off complete, each time we open the doors.”

He added that they looked at a number of 40-taper five-axis machines in a similar price bracket to replace their old machining centre, but they could not compete with the speed of the 30-taper Brother machine.

In fact, the smallest cycle-time saving achieved to date by swapping an existing job onto an S700X1 is 40%.

W1These machines are especially appropriate for CTPE, which processes a lot of aluminium; and while one of the new medical parts is quite large for a 30-taper machine (it is 180 x 50 x 50mm), the Brothers cope with it well, despite more than three quarters of the billet’s material being removed.

The accuracy achieved is down to ±5µm positional tolerance — better than is possible on many 40-taper machines.

Chris Taylor pointed out that CTPE also produces components in steels (including stainless) on the S700X1s, although a 30-taper machine would not be appropriate if one is doing that all day.

On a final note, Alex Taylor said: “Before we bought the Brother machines, other users had commented on their reliability.

“Tooling suppliers, who tend to keep their ear to the ground, reported a similar story — and we have not had any down-time on either S700X1 since they were installed.”

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