Slashing set-up times with quick locking jaws

US-manufactured Chick System 5 workholding equipment, supplied in the UK through sole agent 1st Machine Tool Accessories (1^st MTA) is helping to increase productivity and efficiency at Axminster Tools & Machinery in Devon.

The company is an online and high street retailer of tools and machinery that it imports from global suppliers. However, it chooses to manufacture some machine accessories, notably jigs and chucks, including the popular Clubman SK80 woodturning chuck, in-house to ensure quality.

Historically, standard wind-up vices were used to fixture components for machining on CNC mills and machining centres, but as production levels increased, they became too inefficient. Then a new contract came along that required particularly accurate clamping of multiple small parts, namely steel jaws for chucks.

Conventional vices were not suitable, as it was impossible to present a sufficiently large number of parts to the spindle. An initial workholding solution used a steel fixture plate machined to retain the parts by bolting them individually into position. However, it took two hours to changeover for the next batch.

To provide a quicker solution, 1st MTA proposed its Chick Qwik-Lok system. It significantly reduced set-up times, as the jaws secure components quickly and to high repeatability for milling and drilling. One large part can be clamped between two jaws but to allow more parts to be loaded at a time, more usually a pair of components, or multiples, are held in two stations. Aluminium jaws machined with the profile of the parts to be held ensure they are retained firmly during machining.

Turning a single handle advances the two movable Qwik-Lok jaws simultaneously towards a fixed central jaw to clamp the parts, which also has the effect of cancelling the opposing forces and creating a reliable reference point for machining.

Once Axminster had adopted this procedure, clamping several steel mounting jaws in each Qwik-Lok station, productivity was dramatically increased. The machine operator is able to change up to six Qwik-Loks on a vertical machining centre (VMC) table in half an hour, four times faster than using the bespoke steel fixture plate.

The machinable soft jaws were soon found to be a versatile solution to other clamping problems, such as how to retain chuck bodies without the risk of the cylindrical components rotating during machining. Again, these parts were previously bolted to a fixture plate, necessitating a half-hour set-up time, whereas now the bodies are swapped in the line of Qwik-Lok jaws in a couple of minutes.

Axminster initially decided to mount the units directly onto the machining centre table, but it meant that when a clamp was removed it was time-consuming to realign for a new job. To avoid this, Jake Knight, head engineer at the innovation department at Axminster, decided to invest in a Chick foundation plate for two 3-axis VMCs onsite, a Mazak VCN-530C and one of a pair of VTC-200Ms.

Manufactured to suit the size of the machining centre table, the cast iron plates have a grid of accurately drilled holes at 50mm centres with hardened bushings and threads at each location that allow Qwik-Loks to be positioned anywhere over the surface rapidly to an accuracy within 10µm. The use of round and diamond pins at two positions allows the Qwik-Loks to be located and mounted quickly and easily.

Alphanumeric labelling of the grid enables correct relocation of each base and jaw set so that the same program can be used every time a job repeats. All unused holes in the plate are sealed with plugs to prevent the ingress of swarf, which could compromise location accuracy.

Mr Knight explains: “Overall, we use about 20 Qwik-Lok bases and have three times as many soft jaw sets machined to hold a multitude of components that we machine.

“We have chosen Chick’s 1040 base size, with a jaw width of 100mm and an overall length of 400mm, as this supports a majority of the components and accessories we produce.”

Source: pesmedia