1st Machine Tool Accessories Ltd

Machine Tool
Workholding Specialists

10th April 2010

Kocurek Excavators Unearth Ideal Workholding Solution With Chick One-Lok

One-Lok CNC Vise

Everything about the equipment manufactured by Ipswich-based Kocurek Excavators Ltd is tough – from its arduous operating environments to the aggressive machining strategies used to produce the company’s custom-engineered excavator products.

With roots in the earthmoving and plant hire sector, Kocurek Excavators has amassed more than 25 years experience in developing long reach arms and multi-purpose units that extends the versatility of standard hydraulic diggers – to the point that the company’s products can be fitted to many manufacturers’ standard vehicles without invalidating their warranty.

Kocurek equipment covers applications across industries as diverse as mining, rail, marine, materials handling, mineral extraction, demolition, shaft sinking and tunnelling. In addition, the company offers a wide range of additional fitments to enhance the safety and operation of their modified excavators, including a variety of cab options, seats, additional counterweights, auxiliary fuel tanks and modified vehicle undercarriages.

Kocurek prides itself on a policy of designing and manufacturing virtually all items in house, on the basis that it not only creates work for its own employees, but also provides full control of product quality. Furthermore, modifications and updated designs can be transferred to the shop floor very quickly in order to provide a highly flexible response to users’ requirements.

With customised excavators costing several hundred thousand pounds and civil engineering projects invariably run against short deadlines, the pressure is always on to maximise equipment utilisation on site. That, in turn, necessitates heavy duty components that are made available quickly and accurately, right-first-time.

According to Kocurek’s machine shop supervisor, Ben Woollard, it typically involves the machining of prismatic parts from 30 to 350 mm diameter in mild steel, aluminium bronze and Weldox, a high strength weldable steel.

“The ability to maintain consistent manufacturing quality and throughput has to be based on good workholding – used in conjunction with high capability machine tools,” he says. “At the heart of our machining capabilities are six Haas CNC machines; three lathes and three vertical machining centres. Until recently, we employed traditional knee mill vices to locate components during machining operations, but these proved to be less than ideal.”

“In order to generate the necessary grip to hold parts securely, operators would regularly use a hammer to tighten the vices’ crank handles,” Woollard explains. “That not only tended to deflect the units’ fixed jaws, leading to machining accuracy and repeatability issues, but the leadscrew would also become stretched, making the units increasingly difficult to use. Even so, components could still occasionally work loose under heavy cuts. What’s more, the high loads exerted on the vices have been known to simply fracture their castings.” 

Woollard adds that due to the bespoke nature of Kocurek’s work, component batches rarely exceed 15 units. Accordingly, each operator undertakes several set ups a day. Using traditional vices, they would often find themselves winding the crank handle in and out ‘forever’ to accommodate differently sized components – further compromising set up times and throughput.

“We would typically wear out our old milling vices in around six months,” Woollard adds. “So when we heard about the new Chick One-Lok system from 1st Machine Tool Accessories (1st MTA), we were keen to get our hands on one, just to see if it really could live up to its claimed performance.

“Our first impressions were very good. The unit’s modular design incorporates a precision ground solid base, which not only enhances its rigidity, but also eliminates swarf traps, reducing the need for cleaning between machine cycles. It also offers a number of other novel features that lift it ‘head and shoulders’ above traditional milling vices.”

A key factor is One-Lok’s rugged construction, which enables more than 4.5 tonnes of gripping force to be generated – along with a pull down action – using only hand pressure on the operating handle.

“Since using One-Lok, we’ve never had a component work loose,” Woollard adds. “This has given us the confidence to push up cutting speeds and feeds on several jobs, and trim cycle times as a result.”

The adoption of more aggressive machining strategies can frequently lead to machining quality and repeatability issues. However, One-Lok’s novel ‘squeeze’ clamping action applies an equal and opposite internal force to the fixed jaw as the moving jaw closes, providing virtually deflection free component clamping – even under extreme load.

The need to wind a traditional vice’s handle up to 70 revolutions to fully close its jaws is now a thing of the past thanks to One-Lok’s ‘Qwikslide’ mechanism. This allows the moveable jaw to be easily unlocked and slid forward or backwards to the desired position throughout the equipment’s 430 mm grip range, ready for final component clamping. Likewise, the system’s ‘Boltfast’ interchangeable jaw system enables hard or soft jaws to be replaced in under 60 seconds, with a positional repeatability of 0.02 mm. 

“We’re already taking advantage of this by building a library of profiled soft jaws that complement standard machining programmes on a number of common parts,” Woollard continues.

With the aim of providing next day service on non-stock items, customer service is central to Kocurek’s business. It’s also no surprise that within a month of purchasing its 1st One-Lok system from 1st MTA, the company had ordered a second. A third unit is also expected to be added soon, enabling each of Kocurek’s VMCs to be equipped with its own dedicated unit.

“Overall, there’s just no contest between old style knee mill vices and the One-Lok,” says Woollard. “The Chick unit enables us to produce parts faster, more accurately and cost-effectively than we ever could before. In a word, it is simply ‘excellent’.”

The Chick One-Lok is available from 1st MTA. If you have any questions or queries about the products mentioned in this article, please don’t hesitate to contact us on 0800 783 0510 or enquiries@1mta.com.