Stereolithography material suits direct manufacturing

Developed via the joint efforts of DSM Somos R&D and the Netherlands-based DSM Research group, DMX-SL is based on an innovative technology that produces resins with extremely high impact strength and resistance to breakage.

Somos Product Development Manager Brian Bauman states: "DMX-SL is very different from traditional SL resins. With an impact strength up to 0.71J/cm, yet a flexural modulus ranging from 2000-2400MPa, it has the stiffness of standard ABS-type resins but more than twice the impact strength – plus up to 20 per cent elongation at break."

This closer approximation of thermoplastic-type properties brings SL one step closer to direct manufacturing – that is, the cost-effective direct building of custom plastics parts without the need for tooling. Though SL has successfully been used to date for some specific direct manufacturing applications (eg hearing aid shells, jigs/fixtures for product assemblies and interior products such as custom lamp shades), its widespread use has been limited by material properties.

Performance attributes of DMX-SL 100

• Extreme robustness – impact resistance 0.71J/cm, which is up to four times higher than standard SL materials
• Stability over time – constant impact resistance even after ageing at high temperatures
• Mechanical properties – closer to key engineering plastics such as ABS, nylon, PP and PC
• Superior accuracy and surface aesthetics typical of sterolithography
• Excellent optical and tactile properties – very interesting combination of mechanical properties for prototyping and rapid manufacturing (looks and feels like plastic)
• DMX-SL 100 allows SL technology to be used as a cost-effective alternative to selective laser sintering (SLS) and vacuum casting
• Zero inhibition to common silicone moulding materials
• Suitable for small frame as well as large frame SL machines such as Viper Si2, SLA 7000, Viper Pro, etc.

Bauman comments: "Current SL resins on the market - and there are over 40 between Somos and other suppliers - are more brittle than traditional engineered plastics such as polypropylene, ABS, polycarbonate and nylon. In addition, SL parts often become more brittle over time, which is unacceptable for direct manufacturing applications."

For this reason, while SL resins perform well in rapid prototyping applications, their usefulness in direct manufacturing has previously been restricted to products that do not require much durability.

Accuracy of SL, durability of sintered nylon

Somos Marketing Manager Eva Montgomery says: "We believe Somos DMX-SL 100 is a revolutionary product for the RP industry. Until now, other RP technologies that utilise molten or sintered thermoplastics have traditionally been chosen when part durability was critical, but with a sacrifice in part aesthetics or dimensional consistency. DMX-SL combines the accuracy of SL with the durability of a sintered nylon. Now RP users can have custom-built parts that are durable, accurate, and have excellent detail."

Early users of the material agree. Mark Jones, SL Manager at Laser Reproductions (www.laserrepro.com) in Gahanna (OH, USA) says: "DMX-SL is rigid yet bendable – the perfect combination. Its impact reliability is much more than 'semi-rigid' or 'rigid' materials currently on the market. I have doubled parts over with no breakage. Compared to typical SL materials, DMX-SL is heads above the competition."

DMX-SL 100 parts are now commercially available. Visit the Somos website at www.dsmsomos.com to find a service bureau running this advanced resin.