Breaking with tradition

From an auspicious start in 1862 as a scientific instrument manufacturer, leading jig boring machine producer Société d'Instuments de Précision (SIP) has been through challenging times over the last few decades. Since its acquisition by StarragHeckert in 2006 however, the company is now making a comeback with a new machine range that offers ultra high levels of precision and productivity.

Described by its managing director Jean-Daniel Isoz as ‘the industry reference for precision', the Geneva-based jig boring specialist, with the help of parent company StarragHeckert, has recently entered into the mainstream machine tool market with its new SPC (Super Precision Centre) range.

From the start, SIP's activities have been fully focused on the ultra precision market. Between 1878-89 for example, it was charged with producing machinery capable of making copies of the master metre - a bar kept at the Bureau International des Poids et Mesures in Paris that formally defined the length of a metre - for member countries of the Convention du Mètre.

The company made the move into the machine tool arena in 1920, designing and manufacturing the first ever jig boring machines. With these products it enjoyed sustained popularity for over five decades thanks to a strategy of focusing on attaining as close to mechanical perfection as possible with particular features such as precise geometries designed to be free of tension, a three point machine bed, a closed machine frame and free V and flat guideways precision hand scraped directly into the castings.

The late 1970s however saw a shift in manufacturing philosophy for many of its customers, which Mr Isoz describes as the ‘just good enough approach'. “At this point the market shrunk significantly and SIP decided to focus only at the very top of the pyramid. When I first joined the company, it was facing a difficult financial situation so becoming part of the StarragHeckert Group in 2006 provided the stability we needed,” he explains. 

A change of philosophy

In 2006 and despite producing machinery that was still capable of leading the market in terms of precision, it became clear that a totally new range of products would be essential for SIP's future. With the management, the infrastructure and the funds now in place to support and develop SIP, the business is growing once again.

With administration, purchasing and sales now taken care of by the wider group, SIP employs 40 dedicated engineers at its manufacturing base in Geneva to design, engineer, manufacture, assemble, check and install its products across the market, 10 of which are devoted to R&D. Mechanical perfection is still something the company prides itself on. After all, according to Mr Isoz, “SIP is not just a brand, it's a mechanical design.” In order to develop however, a new business strategy was required, and this is where the SPC range comes in. The machines are the first fruits of the close collaboration between SIP and its new owners, with the Heckert side of the company based in Chemnitz, Germany developing the machine concept and Starrag in Roschascherberg delivering software capability to SIPs core offering. 

A new breed

The SPC range is designed to fit directly in-between StarragHeckert's high productivity and SIP's ultra precision ranges, aiming to offer a better compromise between productivity and accuracy. Thus, where SIP's traditional jig boring range can reach tolerances of under 2.5µm, SPC machines come in at the 4µm mark.

Officially launched at EMO last year, there are currently two variants – the 4-axis 7120 and 7140 models, with the main difference being capacity. The 7120 has a machining volume of 1,200mm x 900mm x 1,200mm in X, Y and Z whereas the 7140 offers a larger 1,450mm x 1,100mm x 1,300mm. However, 5-axis versions will be launched at September's IMTS exhibition in Chicago.

Despite what is effectively a different product concept to SIP's traditional range, SPC machines still contain much of the company's typical design values, with the same attention to detail and mechanical approach as applied to its other machines and production taking place at SIP's temperature controlled Geneva facility. For example, each machine undergoes around 200 hours of hand scraping with the base, linear guideways, ballscrews, spindle heads and axes all treated, offering not only as close to perfect geometry as possible, but also long term precision. In fact, so high is this durability, claims Mr Isoz, that its largest competitor is its own, older machines.

“We had to define the right way to get the most accurate geometry,” he adds. “With machine tools the foundations contribute significantly to the stiffness and rigidity of the machine whereas traditional SIP machines stand alone. This was a new concept to us so we had to adapt, for example, by adopting a specific scraping strategy.”

There has also been extensive design consideration given to thermal management throughout the machine, with the use of additional thermal shields to improve isolation from heat sources, temperature and elongation sensors in key components, active coolant temperature compensation and controlled cooling of the direct drive rotary table, spindle gearbox and ballscrews.

A thermosymmetrically designed bed ensures that the weight and mass of components each side is closely matched allowing for even expansion across the machine and an air stream barrier helps to prevent build-up of air between the floor and the machine interior. With swarf often being the largest heat source in any machining operation, fast removal has also been catered for by vertical stainless steel deflectors and a wide central conveyor. 

What industry wants

Speaking about the decision to change its market strategy, Mr Isoz explains: “We have seen in the last four to five years that even in the aerospace sector, particularly civil, customers are looking for lower cost manufacturing by use of increased productivity and are frequently questioning whether they require such high tolerances on certain parts. That trend is quite new compared to the automotive industry but it has emerged, so we need to be able to offer this functionality. Sometimes part precision is not always everything and instead people are looking for the best repeatability and this is where the SPC range comes in.

“Another reason to launch a machine at this level is the machinery being produced for other industries, which might be in textiles, packaging, or other machine tools where the demand for precision is increasing and these customers need a higher class of machine to get the final product to the desired quality.”

Complementing SIP's main product offering is a substantial retrofit market which, given the typically long life of SIP machines, is a particularly important part of the company's market strategy and is seeing large demand, especially with owners of its former 640 and 740 jig borers. SIP can retrofit any machine up to 35 years old or within reason, either to overhaul machines mechanically or to add CNC capabilities, ensuring that customers can make the most of previous investments.

StarragHeckert
www.starragheckert.com