Accurate dies play vital role for hydroforming company
Haas CNC machine tools are facilitating the in-house production of tools and dies that are essential to Hydroforming Design Light - a Swedish company deploying patented production methods to ‘reinvent’ the hydroforming process.
Hydroforming is a method for shaping malleable metals into lightweight, structurally stiff workpieces using water at high pressure to press room-temperature working material into a die. The process allows complex shapes to be formed that would be difficult or impossible with conventional solid die stamping. Parts produced by hydroforming can also be made with a higher stiffness-to-weight ratio and at a lower unit cost than traditional stamped or stamped and welded parts.
The hydroforming process is a fast growing technology although the process has been around a long time; helmets for the British Army in World War I were manufactured by hydroforming. Now, a Vansbro-based Swedish company called Hydroforming Design Light (HDL) AB, has developed patented machine construction and patented tooling solutions to bring the process up-to-date and make it cost-effective for modern manufacturing.
“In the past hydroforming has been more or less exclusive to industries manufacturing very large volumes [automotive, for example] or sectors with high investment capital availability [such as aerospace],” says Managing Director Alvar Palmcrantz. “This will now change. Our patented machine construction has, with all factors equal, an investment cost that is a fraction of what can be found available on the market today.”
Hydroforming Design Light AB manufactures and assembles its own, high value hydroforming machines, but at present is generating the bulk of its revenue by subcontracting its processes.
“At the moment we are definitely a subcontract company,” confirms Mr Palmcrantz, “however, we already have customers who want to buy our machines, so maybe in a couple of years we could explore this potential revenue stream fully, but not yet.”
Hydroforming stretches material more evenly than conventional forming techniques such as stamping and deep drawing, and results in a more cost effective construction with lower weight – sometimes as much as 50 per cent lower. In comparison with traditional methods, other hydroforming benefits include the ability to draw deeper sections, tooling at less than half the cost of other techniques, less material spring back, higher precision on detail and better surface quality.
Hydroforming Design Light offers three principle variations of the hydroforming process: Tube hydroforming starts with a tube placed in a tool that is then filled with fluid at pressures around 4000 bar until the pipe deforms into the recesses of the tool. Automotive structures, exhaust parts, handles and furniture components are suited to this method. Sheet hydroforming is where sheet material sits on top of a tool and is deflected into the tool profile using high-pressure hydraulic fluid. Many vehicle panels are produced this way. Finally, so called ‘pillow’ hydroforming ‘inflates’ two metal sheets joined by laser welding into the tool. Containers such as fuel and oil tanks are manufactured in this manner.
All of these processes need accurate dies, the production of which until recently HDL trusted to local subcontract machine shops.
“We bought the Haas VF5 CNC vertical spindle machining centre from the local Haas Factory Outlet, a division of Edstroms, primarily to manufacture our tools and dies,” states Mr Palmcrantz. “In the long run, when we have more Haas machines, we will have enough capacity to undertake at least 50-60% of our tooling requirements in-house. A plant growing as quickly as this needs the capability to produce its own tools.”
“We also bought the Haas machine because we want to be very quick to service our customers,” continues Mr Palmcrantz. “One of the impressive factors about the Haas is that we can machine steel dies as quickly as aluminium dies, which we make occasionally for lower volume orders. That said, many of the cavities we machine are extremely complex and it is not unusual for some dies to stay on the Haas for a full day or even two.”
Before parts reach the Haas machine, which is fitted with a TR 210 trunnion table, Hydroforming Design Light uses a ZCorporation Spectrum Z510 machine to generate rapid 3D prints of high definition, full-colour prototypes from CAD models.
“We make 95 per cent of our mistakes at the modelling stage,” says Mr Palmcrantz, “which means we scrap less material and save a lot of time.”
Hydroforming Design Light’s main customer is Volvo Truck, but the potential for this process is vast and the company is currently working on a range of customer projects from ski-poles to telecommunications components and aircraft seat frames. All will benefit from the weight and material savings.
“In another application we manufactured hexagonal framework tubes for radio masts,” explains Mr Palmcrantz. “The design increased component stiffness by 40 per cent. We calculated that for a 30m high mast, our version would weigh 89kg compared with 1400kg using traditionally manufactured parts. With this method the customer could use stainless steel, which although is 4-5 times more expensive than galvanised steel for instance, would still be far cheaper overall.
“Material thickness has nothing to do with component stiffness,” he concludes; “shape is far more influential. There are really very few limitations to hydroforming, perhaps just the imagination of the component designer.”
