Scribe technology makes its mark

Terex Coventry has installed two Technifor XF 510Sr scribe marking systems to automatically provide product identification on the range of Genie scissor lifts produced at its facilities.

As well as improving the product quality the systems also provide a reliable and robust replacement for a manual marking method that was fraught with potential problems.

Following the amalgamation of a number of specialist construction industry businesses, Terex Coventry was formed, and today the company produces dumper trucks and back hoe loaders for civil engineering customers around the globe. Demand fluctuates with market conditions but Terex aims to keep a steady build schedule where possible.

In 2002, Terex purchased Genie Industries, an American company that specialises in the design and production of scissor lifts and aerial access platforms for construction, maintenance and installation applications.

“Like Terex, Genie has a global customer base and following extensive investigation financial and logistical benefits were felt achievable by supplying the European market with locally produced scissor lifts. So, part of the Genie range was planned for production in the Coventry facility, a major step because Genie had never previously made any of its products outside USA,” recalls Patrick McGrath, Senior Manufacturing Engineer.

Terex Coventry employs over 600 people, working on the shopfloor on a single shift, of which over 120 work in the scissor lift production area. Built on two production lines that run in parallel and duplicates the systems and facilities used by Genie in America, the first line produces four smaller models while the main line builds two varieties and four different models

“While we had lean practices in place, Genie Industries had taken scissor lift assembly efficiency to the next level and we had to train our staff to match these philosophies. We are also tight on space here, so we had to re-engineer the assembly line to fit into a limited floor area. While we altered certain aspects of the assembly line we also considered issues on the product, and one of which we wanted to address was the marking of the chassis identification number,” says Patrick McGrath

Manufacturing Engineer, Mick McKean, explains that each scissor lift has a visual identification on its chassis similar to a VIN plate on a car. He says: “The method transferred from Genie Industries relied on an aluminium jig block to hold and space the number and letter punches that the technician then had use to mark each chassis in two places. Being a manual process there's little or no quality control. The stamped mark was completely subject to the skills of the person creating it, and because the identification is applied after the electro static powder coating the percussion effect of the punch was causing quality issues with paint chipping and subsequent corrosion when the customer used the scissor lift in the field.”

There were also obvious health and safety concerns regarding lifting and holding a jig block and repeatedly hammering punches to create the identification mark directly into the 6mm thick chassis material. “We looked at various methods of creating the string of characters needed for identification and an extensive evaluation of the market resulted in contact with Technifor. We did consider percussion indent marking technology but noise constraints narrowed the selection to scribe marking, which is very clean and virtually silent in operation,” Mick McKean explains.

The XF 510Sr scribe marking head supplied by Technifor was subsequently engineered for production by Mick McKean and his team, making it extremely safe and easy to use. This included fitting the scribe unit to an overhead track with a spring balancer so that it can be manipulated easily around the cell, and also a quick clamping device so the unit can be attached to the scissor lift chassis.

Within the assembly cell a barcode on the route card is scanned, and this system automatically transmits the instructions for the Technifor XF 510Sr scriber to mark the correct string of characters required for identification. There is no setting or typing required, which removes the opportunity for human error, as with the old stamping method there were concerns with duplicate identification numbers.

A lip on the chassis provides an ideal location point for the scribe unit and two toggle clamps are used to lock it in position. The marking process had to be quick to stay within the Takt time, and while the unit can mark in just 8 seconds per location Terex has slowed it down to around 30 seconds, as the operator is completing other tasks and is not waiting for it to finish

The first scribe unit was installed in December 2011 and the second went into the production cell during January 2012. The XF 510Sr scriber is fitted with the Technifor standard diamond tipped stylus and because it is marking in high tensile chassis material, Terex has a spare. The expected life for the tips is 7.5 million characters, which Mick McKean has calculated is 3.5 years worth of marking.

He says: “The quality of mark generated is superb. We still mark through the paint finish and then apply a high contrast wax, which seals the surface to protect against corrosion and also increases visibility. We operate in a people heavy environment so the opportunity for damage is high but we are very happy with the Technifor scribe markers because they are one of the very few pieces of equipment that we don't get called out to repair, they are robust and just work really well.”

Due to the success of the scissor lift production lines in Coventry, a completely new Genie model has been introduced for the European, Middle East and South African markets. Meeting the demand for a unit with a 40 ft reach and increased working capacity the new GS-4047 will only be produced in the UK. “It has been extremely well received at the various trade shows it has been demonstrated at,” concludes Patrick McGrath.