Multi-axis mill-turning at MTE

Posted on 02 Aug 2017 and read 1423 times
Multi-axis mill-turning at MTEFollowing the recent installation of the latest Miyano multi-axis mill-turn centre, the Wednesbury-based precision sub-contractor Machine Tech Engineering (MTE) has been able to slash production lead times on batches of hydraulic bodies from four weeks —three for the first operation and one for the second — to just five days.

The decision to go for the 51mm-bar-capacity Miyano BNE-51MSY from Bushey-based Citizen Machinery UK Ltd (www.citizenmachinery.co.uk) was based on continuing the benefits being achieved by installing new machines — such as a recently purchased Citizen A32-VllPL CNC sliding-head mill-turn centre, which helped secure an order from a new customer in the brewing industry for batches of 1,000 stainless-steel pump valves.

MTE director Warren May said: “Without this Citizen, we would never have dreamed of even quoting for such parts, as we would have been uncompetitive, but the machine is both quick and powerful — and it allows the use of simultaneous cutting cycles.”

MTE, which aims to break the £1 million turnover mark this year, has some 30 machines — including seven under the Citizen brand — in its 7,500ft2 machine shop.

The company’s more recent CNC sliding-head installations, which allow it to combine several operations into single cycles, were the result of a visit to MACH 2014 at the NEC.

MTE director Stewart May said: “We saw a sign on the Citizen stand promoting a 20% regional grant. This chance sighting changed our business, as the grant — combined with the ability to run a Citizen A32-VllPL unmanned — eliminated any fears about affordability.

“We bought one of these machines and had filled its capacity within three months — so we bought another!”

While MTE’s sliding-head machines are highly productive and run essentially unmanned, they have a maximum capacity for bar up to 32mm in diameter; and while the fixed-head lathes that the company was using accommodated sawn billets up to 300mm in diameter and 1,200mm long, they required continuous operator involvement.

Warren May said: “We could see the market changing — with work coming back from overseas — and knew we needed to become more efficient on bar work beyond the capacity of our sliding-head machines.

MTE“We headed to MACH 2016 with an open mind, but we were drawn immediately to the newly launched Miyano 51mm-capacity BNE-51MSY fixed- head turn-mill centre on the Citizen stand.”

Both directors later went to Citizen’s October Open House to have a closer look at the Miyano machine and see it ‘put through its paces’.

They subsequently placed an order for one. Stewart May said: “As soon as the machine was installed, it made some of our second-operation machines and equipment redundant.”

Early days


MTE was founded by the two May brothers in 2002. They started with two fixed-head lathes and specialised in very-small-batch work. They soon added nine cam autos before acquiring a used Citizen E20 in 2004, which is still in production.

Stewart May said: “It has now produced hundreds of different jobs and still holds 0.025mm tolerances and high levels of surface finish throughout an 8hr shift — impressive for an older machine.”

MTE’s success resulted in several moves and additions to its various premises over the years, until it moved to its current site in 2012. MTE now has some 80 ‘live’ customers.

Commenting on the company’s expansion, Warren May said: “ As the recession was biting in 2008, we felt we were becoming ‘pooper scoopers’; because we were a lean operation with low overheads, customers were flocking to our door offering work at low prices.

“We picked up a lot of orders, albeit for work that our competitors wanted to avoid. However, we were able to extend our customer base and gain more expertise. This led to future work — and greater profitability, as we introduced newer machining technology.”

MTE’s customer base now comprises: automotive (including the manufacture of special tools and spares for out-of-production classic vehicles), hydraulics, security, special fasteners, injection moulders, petrochemical and medical.

As a result, the materials processed include carbon steels, stainless steels, brass, Tufnol and phosphor bronze.

The company now employs nine people, and both Stewart and Warren are involved in setting machines — as is Stewart’s son Ashley, who is a former apprentice. Batch sizes on the Miyano are currently between 100 and 300, while batches on the Citizens vary between 500 and 60,000.

Lead time reductions


The eight-axis Miyano BNE-51MSY, which is fitted with an Iemca Kid 80 bar feeder, has given MTE significant reductions in lead times, due to the ability to overlap operations in a cycle and cut with up to three tools simultaneously.

The machine has two 12-station driven turrets; the upper turret has three axes (X1, Y1 and Z1), while the lower turret has two (X2 and Z2) — and both turrets can access one or both spindles at the same time.

The main spindle has a 15kW drive, while the second (two-axis) spindle is powered by a 7.5kW motor.

Both have a 51mm capacity and a maximum speed of 5,000rev/min. The driven-tool positions for milling and drilling are rated at 2.2kW (25Nm of torque) and have a maximum speed of 6,000rev/min.

When producing the hydraulic body mentioned at the start of this article, MTE starts with a 38mm-diameter bar. The first operation is to use a 22mm spade drill to produce a 57mm-deep hole; this is followed by a special flat-bottom tool that faces the bottom of the bore and machines a corner relief, prior to the bore being finished to size.

Next, a further bore is drilled and reamed 11.9mm in diameter x 76mm deep, and the initial bore is threaded 1in-20TPI Whitworth x 8mm deep. The OD is then turned and threaded 1.5in-16TPI Whitworth x 100mm long.

The part is then taken by the two-axis secondary spindle, faced and a 20mm-long 30mm A/F hexagon is milled. This operation is followed by the machining of a 6mm shoulder that is straight-knurled.

A through bore is then drilled to break into the 11.9mm bore and tapped 7/16in-20TPI UNF to a depth of 26mm.

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