Heavy Machining for Even Heavier Lifting

Hi-Force Ltd. (Daventry, UK) now uses 12 machine tools from DMG MORI Company, Ltd. (Coventry, UK) after installing a new SL-603 two-axis heavy duty lathe for machining hydraulic cylinders of up to 1,000 tons lifting capacity. A remarkable success story, this company has increased its sales revenue by 20 percent year-on-year by supplying a wide range of hydraulic tools around the world from its Daventry headquarters. The Hi-Force range of high pressure hydraulic bolting and lifting products is used every day in the oil and gas, power generation, railway, construction, heavy engineering and shipbuilding industries, and is designed to apply controlled loads in heavy jacking applications and leak free flange connections using hydraulic power for controlled bolting.

Their first DMG MORI investment, back in 2009, moved manufacturing of subcontracted parts in-house to provide control, reduce costs and shorten delivery times. The latest investment in the SL-603 lathe opened the door for competitive manufacturing of component parts for large capacity and special design cylinders, which were previously being subcontracted. “For very large machined parts, we needed to achieve much shorter delivery times and cost reductions,” explained Kevin Brown, the group managing director of Hi-Force. “Subcontracting is, and will remain, an integral part of our manufacturing supply chain. But the type of equipment necessary to economically and quickly machine these large cylinder components was not always available, resulting in high manufacturing cost and long lead times.”

The shop worked closely with DMG MORI to arrive at a specification of machine tool which would be powerful and big enough for its plans. “Our experience with them has been excellent and we had absolute faith in the solution they proposed,” added Brown. “We allocated two of our best machine setter/programmers to the project and they went to Japan to see the SL-603 lathe under construction and to undergo comprehensive operational training.”

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The decision to invest has proved to be a wise one. Since installing the SL-603 lathe, the company has seen a surge in orders for large cylinders, notably a $2 million order for a Middle Eastern metro project for 146 off 500 ton cylinders and 26 off 1,000 ton cylinders, which means that 85 percent of the production capacity of the SL-603 lathe was allocated between March-June 2015. The design of these cylinders required the SL-603 lathe to remove large amounts of material quickly and accurately, starting with a solid steel billet weighing 1,400 kg that required the machining of a “blind hole” bore in the center of the billet. The finished and fully machined cylinder body weighed only 800 kg. This major machining operation, which removed approximately 600 kg of material, was achieved in less than 4.5 hours per piece.

The SL-603 lathe has a 37 kW spindle and driven tools. The first operation is to bore out the cylinder. For this, the shop uses a Kennametal HTS 220 mm diameter drill straight into the billet to make the first cut. “The capacity of this drill and the power required to drive it would stall the spindles on our other DMG MORI NL lathes. Seeing a drill remove 220 mm diameter of material in its first cut is very impressive,” noted Chris Dickinson, the operations director at Hi-Force. “We also use Sandvik Coromant tuned boring bars that can take 3.5 mm depths of cut 700 mm deep with no vibration. Even more amazing, we then drill a 2 mm diameter bleed hole through the 70 mm thick side wall of the cylinder. The SL-603 lathe has the power for massive metal removal rates, yet it also has the accuracy and stability to drill the smallest of holes.”

To maximize productivity and flexibility, Capto tooling is used to switch tools in the turret with just one easy fix and release screw. Load monitoring for tool wear and tool probing ensure that sister tools can be switched over in plenty of time. Tips can then be replaced or turned while the machine is running further minimising expensive downtime. “As part of the commissioning of the machine, DMG MORI worked with us to develop our machining processes, helping us to build up our confidence when using a machine with this much power,” added Dickinson.

To complete the manufacturing cell for these large cylinders, the shop also invested in a cylinder bore honing machine from Delapena Honing Equipment Ltd. (Cheltenham, UK). By locating this equipment right next to the SL-603 lathe, the machined parts can be craned straight into the honing machine, which has the capacity to hone bores up to 600 mm diameter.

Thanks to the SL-603 lathe, the shop is able to extend the range of sizes in its cylinder catalog and also offer a special cylinder design and manufacturing service. Now it can achieve delivery times of as little as four weeks for large and special cylinders for its customers located in over 100 different countries. The company currently has regional offices in Europe, the Middle East, Asia and Africa, with expansion plans for the Asian facility and introducing local training at all of their regional offices worldwide.

“We have massive confidence in this lathe and their after-sales service, and will always look at them first,” concluded Brown. “The growth in our business is testament to the success of our investment strategy, enabling us to deliver customer satisfaction and continuity of supply.”

Hi-Force Ltd., Prospect Way, Daventry NN11 8PL, United Kingdom, +44 1327 30 1000, www.hi-force.com.

DMG MORI Company, Ltd., 4030 Siskin Parkway East, Middlemarch Business Park, Coventry CV4 4PE, United Kingdom, +44 2476 51 6137, Fax: +44 2476 51 6136, www.dmgmori.com.