The Cliffhanger process.
The Cliffhanger process.

The world's manufacturing industries are constantly looking at new ways to reduce production costs and development cycles in order to remain competitive. This is nowhere more so than in the automotive industry, where ever tighter time-to-market schedules for new vehicles have to be balanced with the growing consumer demand for better customer choice at the best possible price. All this is combined with the need to conserve resources and minimise waste at all stages of production.

Working with leading manufacturing industries, Huntsman Advanced Materials is helping to address these issues through the development of new prototyping materials and production technologies. Its latest innovation is a versatile computer-aided casting system, Cliffhanger™ that enables large or multiple tailor-made automotive parts to be cast in a single shot, minimising production time, materials and waste.

Traditionally, components used for design or data control models have been produced from solid board materials or by netsize casting. The use of boards reduces production timescales as they can be bonded together immediately and machined as soon as the adhesive has cured. However, this process is fairly labour intensive as it involves cutting the boards to size, bonding them together and then often further work on the bond line. This process also produces a relatively large amount of waste, with a lot of material being machined away in order to obtain the desired dimensions.

Netsize casting involves the production and siliconisation of a Styrofoam mould which is then filled with a liquid plastic material and cured. This process results in a component that is very close to the required dimensions and, therefore, needs much less final machining and finishing. It also eliminates the need for the bonding procedures required when using boards. However, the disadvantage of conventional netsize casting is the production of the Styrofoam mould. This is not only time consuming and costly but also raises some environmental issues as once the part is cast and cured, the Styrofoam mould has to be removed and disposed of safely.

By offering the Cliffhanger Casting System and a range of specially developed RenTool® casting materials to be used with it, Huntsman Advanced Materials enables manufacturers to continue to benefit from the versatility of traditional netsize casting with the added advantage of minimising costs, time, materials and waste.

The Cliffhanger system uses computer aided design (CAD) data to control its flexible, adjustable casting floor made up of hundreds of pins. The height of these 50.5 mm x 50.5 mm pins can be adjusted so that they form a negative mould, very close to the required final dimensions of the part, including an offset the customer needs for machining. This eliminates the need for the production (and subsequent disposal) of individual negative moulds for every part. It simply produces a seamless component, similar to its final required shape and the cavity can be re-utilised several times.

How does this process work?

The customer transmits via Odette line, a slightly converted CATIA file to the Cliffhanger system. Here, the computer-controlled program guides an adjusting slide which, in turn, regulates the height of the individual pins and forms a negative mould. Depending on the size of the casting frame, several parts may be cast simultaneously or a very large part cast in one shot.

After all the pins have been adjusted correctly, the casting frame is moved from the adjusting position to the casting position. In order to protect the pins and to avoid penetration of the casting liquid, a separation foil is placed onto the pins and vacuum-adjusted.

Following the preparation stage, the actual casting of the parts is completed. This requires specially constructed casting equipment which draws a constant vacuum during both the mixing and the metering procedures to ensure the components are completely void-free. A significant factor in the quality of the finished parts is not only the mixing process but also the actual metering of the casting liquid into the Cliffhanger mould. After polymerisation, the parts are removed and tempered, if required.

Huntsman Advanced Materials offers a range of RenTool casting materials, which has been specially developed for use with the Cliffhanger technology. The main applications are in the design of cubing and data control models, forming dies, moulding dies, gauges and tools for galvanoforming. These processes are widely used in the automotive industry, as well as in aerospace applications where production and development costs and schedules are also coming under increasing scrutiny.

Summary

Cliffhanger is the next generation in casting technology for component manufacturing. It minimises cost, materials and waste for customers, delivering a seamless, high quality model or part that requires little additional finishing. While electronic transmission of customer data straight to the Cliffhanger system minimises time input and development cycles.

Cliffhanger is already in use with some of Europe's major automobile manufacturers for production of prototype parts and complete concept vehicles.

Case study

Huntsman Advanced Materials' Cliffhanger casting system and its range of specially developed RenTool casting materials provides customers with a unique tailor-made rapid tooling system for medium- to large-sized parts and is particularly appropriate for the automotive industry.

Some of Europe's major automotive manufacturers are already making use of the Cliffhanger casting system for the production of prototype parts and the development of new models.

One automotive manufacturer has used Cliffhanger to produce large prototype component parts for the wing of a new car.

Using Cliffhanger delivered a 30% manufacturing cost saving over traditional foundry processes. With the electronic transmission of the company's design data straight to the Cliffhanger system, time input and development cycles were minimised, reducing prototype production time on the project by three weeks.

Cliffhanger has also been used to build a Michelin-Award winning model car. Designed to meet the demands of 21st Century urban living in China, the Xin Lang was one of five innovative scale-model car designs selected as winners of the Michelin Design Challenge and exhibited to great acclaim at the Detroit Car Show in 2005.

Xin Lang was designed by the young Slovenian car designer Uros Pavasovic and because of its size, could be cast in a single shot using the Cliffhanger system. A 1500 mm x 500 mm x 450 mm solid block was cast using RenTool 5150 resin. This block, weighing approximately 300 kg was then transported to Slovenia, where it was CNC machined to its final dimensions. The model was then spray coated twice, after which a primer was applied. Finally the model was painted with metallic automotive paint, producing a high quality gloss finish, ideal for public display.