Turning centres double employee productivity

Challenger Hydraulics has doubled the productivity of each of its employees over the past four years by installing Colchester-Harrison lathes.

Challenger cost-efficiently manufactures hydraulic cylinders for the construction, baggage handling and agricultural sectors.

The company has recently become a prime supplier of cylinders to manufacturers of specialist trailers now being adopted in the retail sector for more cost-effective distribution.

The Dewsbury-based manufacturer designs and produces a range of bespoke and standard single and double acting, cushioned and through rod-type cylinders, rams, glands and valves to suit applications with cylinder requirements between 20 and 350mm bore diameters.

Its cylinders can be specified with strokes up to 2000mm and working pressures up to 450 bar.

The company also fits cartridge valves, limit switches and linear potentiometers into cylinders according to customer and application requirements.

Production is aided by five Colchester-Harrison lathes, the latest being a package comprising a Tornado T8 slant bed two-axis machine with 260mm maximum turned diameter and a flat bed Multiturn 2000 combination lathe installed last year.

There are also three Harrison Alpha combination lathes, a 1550 XT with Turnmate I conversational programming package installed earlier in 2007 and an Alpha 550 without auto-cycling capability, purchased in 1997.

The company also uses an ageing Colchester Mascot 1600 centre lathe.

Sales director Sam Pepper compared the very basic Alpha 550 with last year's Alpha 1550 XT now loaded with a full CNC capability for small batch work and quick-change toolpost.

He said: 'Even allowing for inflation, this latest Alpha cost us little more than the 550 a decade ago!' Challenger Hydraulics points out the case for constantly reducing machining lead times, which puts metal removal, a high finishing capability and precision grooving and threading as fundamental to its turning operations.

Pepper added: 'We are so busy and have to meet ever-shorter deliveries so could never tolerate an unreliable machine or one that causes us any sort of bottleneck.

'We need equipment that performs because we have to produce parts faster, a reason why we have relied on one supplier.' The Colchester-Harrison machines have to turn a range of materials including GS 250 cast iron, EN8, EN14, stainless steel and ST52 tubing.

Tolerances tend to be around 0.05mm, mainly on seal grooves with surface finishes of 0.8 micron RA.

According to Mr Pepper, threading is a critical area of the products with pitches between 1 and 5mm using preformed inserts.

This is an area where his setter operators are full of praise for the Tornado T8, Multiturn and two Alpha combination machines for their simple programming at the control to obtain a perfect thread first time.

The Tornado was also praised for the 22kW power, torque and rigidity that enabled a 57mm U-drill to be penetrated from solid some 150mm deep at 800rev/min and with feed rates between 0.12 and 0.15mm/rev according to the type of material being machined.

Cuts up to 3mm deep are taken without any vibration or protest.

The Tornado T8 is also used to machine cast iron glands, locking rings, nuts and bearing rings.

For the new trailer business, cylinders with internal threads of M162 by 3mm pitch are produced in batches of up to 100 parts.

The Multiturn 2000 produces piston rods up to 3m long turned from 50mm diameter material and in order to machine both ends on the 2m bed length, material is passed through the headstock and supported on a steady and rollers.

Over 150 programs are now held in memory and the operators make extensive use of the canned cycles for grooving and threading.

The largest batches produced under the CNC recycling capability tend to be up to 100.

The Alpha 1550XT is also widely praised by the operators for having an ideal mix of power and simplicity at the Fanuc Oimate TC control with Turnmate I conversational programming.

They have found it gives ultra-quick lead time from drawing to machining and the automatic cycling of batches, which rarely exceed 30 parts, is a bonus.

Cylinders up to 300mm diameter by 1.3m long are machined on the older Alpha 550 Plus which is operated by one of the final year apprentices.

Such was the level of simplicity, even on a 10 year old machine, the apprentice was fully competent in three weeks.

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