Sliding ahead to success

 
Following the recent installation of the latest Miyano BNE-51MSY multi-axis mill-turn centre, at the Wednesbury-based precision subcontractor MTE, the company has been able to slash production lead-times on batches of hydraulic bodies.

The new machine means production times have gone from three weeks for the first operation on the hydraulic bodies – plus a week for the second – to machining the batch complete in just five days.

The decision to go for the 51mm bar capacity Miyano continues the already accrued benefits from introducing new machines from Citizen, including a A32-VllPL CNC sliding head mill-turn centre installed to fulfil a contract from a new customer in the brewing industry for 1,000 batch quantities of stainless steel pump valves.

According to MTE director Warren May: “Without the Citizen we would never have dreamed of quoting for such parts as we would be uncompetitive. But the Citizen A-Series is very quick and powerful enabling simultaneous cutting cycles.”

Combined operations

MTE has 30 machines, seven bought under the Citizen brand in its freehold 7,500ft² machine shop from which turnover is projected to top £1 million in 2017. With recent CNC sliding head installations, MTE had already benefitted significant business increases and improvements in productivity from the ability to combine operations into single cycles which came about following a visit to MACH 2014 at the NEC.

Fellow director Stewart May says: “We saw a sign on the Citizen stand promoting a 20% regional grant. That chance sighting changed our business as with the latest machines, we knew if we could afford it we could be confident to run unmanned and so ordered a Citizen A32-VllPL. Within three months we filled its capacity and bought another.”

However, Stewart maintains the company’s confidence in unmanned running was restricted to 32mm bar diameter with the sliding head machines while the company’s existing fixed head turning capability catered for parts up to 300mm diameter and 1.2m between centres based on billets or sawn lengths of bar. This had the disadvantage of requiring continuous operator involvement.

Warren adds: “We could see the market changing with work coming back from overseas so we needed to be more cost-efficient otherwise we could be left behind. We decided to go to MACH 2016 and check out how to effectively expand our bar capacity for single operation production.

“We looked around the show with a complete open mind but were drawn back to the Citizen stand and the newly launched Miyano BNE-51MSY fixed head turn-mill centre. Its 51mm bar capacity left us very positive about the way forward.”

Subsequently both directors decided to make their way to Citizen’s open house to place the order. Stewart says: “From the day it was installed we have never looked back and it immediately made some of our second operation machines and equipment redundant.”

MTE was originally founded by the two brothers in 2002 specialising in very small batch work with two fixed head lathes and eventually adding up to nine cam autos to the plant list. They acquired a used Citizen E20 in 2004 which is still in production. Stewart comments: “It will still hold 0.025mm tolerances and surface finish throughout an eight-hour shift. This is impressive performance for an older machine.”

Another early Citizen L20 produces the same component on a 20,000 a month contract alongside the only BSA cam auto still resident in the plant.

Stewart continues: “The BSA cannot be beaten on cycle time and although the Citizen is running at almost double the time, at the end of the day without any machine adjustments being made, twice as many Citizen made parts are in the finish bin. Most important, all are to size and without a single part-off pip that needs subsequent removal.”

As order books have grown, MTE’s live customer base is now around 80 firms. The subcontractor has had to move or add premises several times over the years as business has grown – moving to its current site in 2012.

Warren says: “As the recession was biting in 2008 we felt we were becoming what we call ‘pooper scoopers’. Because we were such a lean operation with low overheads, customers were flocking to our doors for quotes seeking reduced prices. As a result, we picked up a lot of orders, but in retrospect we can see many of the parts were what our competitors wanted to avoid. However, the work extended our customer base and helped us gain more expertise.”

The current customer base covers automotive, including the manufacture of special tools and spares for classic vehicles. Other sectors include hydraulics, security, special fasteners, injection moulders petrochemical and medical. Materials processed include, carbon and stainless steels, brass, Tufnol and phosphor bronze.

The firm’s future strategy is to keep growth under firm control and plan to be investment led, so as to improve profitability.

Now employing nine people, both Stewart and Warren are involved in setting machines as well as Stewart’s son Ashley. While the headcount is small, it is highly skilled and much of the work involves resetting machines for 75% of repeat orders. Batch sizes on the Miyano so far have been between 100-300, while each Citizen has varying batch sizes between 500 and 60,000. Most repeat orders involve machining for controlled stockholding which can extend the run time between settings and enables a fast response to customer delivery.

Lower lead-times

The 8-axis Miyano BNE-51MSY with Iemca Kid 80 bar feed has created a significant advantage in lead-time reduction for MTE due to the ability to overlap in a cycle and cut with up to three tools simultaneously. The machine has two 12-station driven turrets one with three axes, the other with two that can service either or both spindles at the same time.

The main spindle has a 15kW drive and the secondary 2-axis spindle is powered by a 7.5kW motor. Both spindles have a 51mm capacity with a maximum speed of 5,000rpm. Each driven tool position is ideal for milling with a 2.2kW high torque 25Nm drive and programmable speed of 6,000rpm.

In producing a hydraulic body from 38mm bar, a 22mm spade drill is used to a depth of 57mm, then using a special flat bottom tool a face and corner relief is created at the bottom of the bore prior to final boring to 0.03mm size. A further bore is then drilled and reamed 11.9mm diameter to a 0.03mm tolerance by 76mm deep and the initial bore threaded 1” x 20 TPI Whitworth by 8mm deep. The OD is then turned and threaded 11/2” x 16 TPI Whitworth over 100mm length.

The part is then taken by the 3-axis secondary spindle, faced and a 30mm A/F hexagon milled by 20mm long and a 6mm shoulder created which is straight knurled. A through bore is then drilled to break into the 11.9mm bore which is then tapped 7/16” x 20 TPI UNF by 26mm deep.

Such are the productivity gains with the new machine at MTE that both directors are now reviewing other fixed head operations and especially the on-cost of the additional secondary machining tasks which could be dropped into single hit cycles.

CITIZEN www.citizenmachinery.co.uk MTE www.machinetechengineering.co.uk