RP material suppliers offer new products that can improve your manufacturing processes and subsequently bolster product quality.

CobaltChrome
dental crowns and bridges are being built in an EOSINT M 270 with
direct metal laser sintering (DMLS). The process allows individually
customized dental prostheses to be manufactured in batches of several
hundred at once.

In today’s fast-paced manufacturing world, it seems that new metal materials for rapid prototyping (RP) continue to emerge to address innovative processes and production lines in a variety of industries. For instance, a number of different materials are available for use with EOSINT M systems. They offer a range of electronic manufacturing applications. In particular, EOS CobaltChrome SP1 is a cobalt-chrome-molybdenum-based super-alloy powder, which has been especially developed to fulfill the requirements of dental restorations. 

EOS CobaltChrome SP1 is a Co, Cr, and Mo-based alloy in fine powder form. Its composition corresponds for type 4 CoCr dental material in EN ISO 16744 standard. It also fulfills the chemical and thermal requirements of EN ISO 9693 for CoCr porcelain-fused metal (PFM) of dental materials (Ni content: <0.1%, no Cd or Be) and requirements of EN ISO 7504 and EN ISO 10993 regarding the biocompatibility and cytoxity of the dental materials.

This material is ideal for producing dental restorations such as crowns and bridges. Standard processing parameters use full melting of the entire geometry with 20-µm layer thickness, but it is also possible to use alternative building styles to increase the build speed.

Another material available for use with EOSINT M270 systems is EOS Titanium Ti64, a titanium alloy powder. This material is a pre-alloyed Ti6AIV4 alloy in fine powder form. It is characterized by having excellent mechanical properties and corrosion resistance combined with low specific weight and biocompatibility. The extra-low interstitial (ELI) version has particularly low levels of impurities.

Titanium Ti64 is well suited for many high-performance engineering industries such as aerospace, motor racing, and the production of biomedical implants. Parts built in EOS Titanium Ti64 fulfill the requirements of the American Society for Testing and Materials (ASTM) F1472 for Ti6A12V and ASTM F136 for Ti6A14V ELI regarding maximum concentration of impurities.

Standard processing parameters use full melting of the entire geometry. Parts built from EOS Titanium Ti64 can be machined, spark-eroded, welded, micro-shot-peened, polished, and coated, if required. Unexposed powder can be reused. Typical applications include:

• Direct manufacture of functional prototypes,small series products, and individualized products or spare parts.
• Parts requiring a combination of high mechanical properties and low specific weight such as structural and engine components for aerospace and motor racing applications
• Biomedical implants

A titanium
humeral mount for an arm prosthesis was produced with direct metal
laser sintering (DMLS) from Ti614V within hours. Despite highly complex
shapes, DMLS produces such components in a single build process.

EOS recently exhibited new metal materials at the Rapid 2009 Conference and Exposition including Nickel Alloy 718. It is highly resistant to chloride and sulfide stress corrosion cracking. Also, Nickel Alloy IN 625 is a nickel alloy that is resistant to oxidation and corrosion. The company claims that it is strong at high and low temperatures and is well suited for aerospace and chemical processing applications. NickelAlloy HX is a high-temperature, corrosion-resistant Hastalloy able to withstand harsh environments. Nickel Alloy8 is a precipitation hardened nickel-chromium alloy. It combines high strength in an aged condition with good corrosion resistance and weldability.

In other news, Laser Reproductions joined with stereolithography resin producer DSM Somos and metal plating expert RePliForm Inc. to offer Metal Clad Composite (MC2) prototypes, which merge two technologies to create metal parts without machining.

The prototyping process forms a part from high-strength Somos stereolithography (STL) resin and adds RePliForm nickel plating to produce a highly stiffened composite with enhanced physical properties. The resulting prototypes reportedly can replace those machined from aluminum, zinc, and magnesium in prototyping, and low-volume production applications at a reported cost savings of 90%. 

Using this process, the choice of resin can make a difference in the final result. In general, the stiffer the STL resin, the stiffer the metal clad composite will be. Stiffness can also be improved by applying a thicker metal layer to the part. RepliForm focused on post-processing techniques for obtaining the best metal plating results, as well as on how to adjust STL files to account for the metal plating of the part while still meeting tight tolerance specifications.  For example, assemblies with tongue and grooves normally allow for 0.006-in to 0.007-in clearance. Adding a 0.002-in to 0.003-in metal layer to both the tongue and grove could cause interference and require adjustment.

Advanced Laser Materials, LLC, a developer and manufacturer of materials for RP, recently introduced a new fire-retardant polymide called FR-106. It is a material for use in the laser sintering and rotational molding processes. The material passes the 60-s vertical burn test as outlined in part 25 of the Federal Aviation Requirements while maintaining its mechanical properties. Parts fabricated from FR-106 maintain in excess of 35% elongation to break while continuing to offer excellent resistance to flame propagation.

This material for laser sintering enables part manufacturers to produce high complexity fire retardant nylon parts. In addition, designers can reduce part counts in assemblies, and realize cost savings in short run production applications through direct manufacture and the elimination of high cost tooling. The material strength helps engineers to fabricate part designs with minimal wall thicknesses. This can help reduce weight in the final design, as well as provide the necessary
flexibility for survivable, lasting snap fits, hinges, brackets, and clips.

Manufacturing alternatives
Stereolithography apparatus uses a UV laser to trace a cross section of a product layer by layer across the top of a vat of liquid polymer. This hardens a thin layer of the material. As each layer is traced, the object is lowered slightly for the laser to trace the next cross-section of the object in the polymer, solidifying that layer and bonding it to the previous layer. This is done layer by layer until the part is formed.

Selective laser sintering (SLS) uses a laser to fuse or sinter a thin layer of powdered material into a solid object. After each layer is completed, a thin layer of the powdered material is spread across the top for fusing of the next layer. It is a good process for fine detail and thin-walled parts.

Fused Deposition Modeling (FDM) uses a temperature-controlled head to extrude and deposit thermoplastic material based on CAD cross-section slices. The material starts in a semi-liquid state, bonding to the previous layer, and then hardening.

Solid Ground Curing (SGC) prints each CAD cross-section slice on a glass photo-mask using a electrostatic process such as a photocopier. A UV light shines through the mask onto a thin layer of polymer, hardening the exposed resin. Liquid resin is vacuumed off and liquid wax which is later removed is spread onto any spaces. This layer is cooled to a solid and then milled to thickness. Repeating the process with the next layer builds up the part.

Laminated Object Manufacturing (LOM) starts with a thin layer (4-8 mils) of sheet material and uses a laser to cut the first CAD pattern (based on a part cross-section). A blank sheet backed with a dry adhesive is then rolled across the cut layer and heat bonded. The cutting process begins again on that sheet. The process builds parts with relatively thick walls.

Inkjet Technology deposits tiny droplets of hot liquid thermoplastic in the desired pattern, layer by layer. Droplets of this or another secondary material generate any support structure that is later melted away, dissolved, or physically removed.

Direct Shell Production Casting (DSPC) produces ceramic casting molds for metal casting using a layered printing process that deposits a liquid binder onto a layer of ceramic powder. After the mold is “printed,” it is then fired. These molds will handle any metal and are said to be more accurate than those from sand casting.

Direct Metal Deposition (DMD) uses a CNC laser to fuse layers of metal powder. The resulting prototypes made from H13 tool steel, aluminum, and other metals are meant to be used for
production.

Precision Metal Deposition (PMD) flat wire metal deposition technology uses an energy source such as a laser, to fuse a solid metal flat wire to a substrate.

3D Printing is a term applied to several similar technologies for machines that often operate in an office setting. Some companies use a FDM-like technology with a polyester material. Others use an inkjet to print glue onto layers of loose ceramic (alumina) powder to build casting molds.

EOS
www.eos.info

Laser Reproductions
www.laserrepro.com

DSM Somos
www.dsm.com

Repliform
www.repliforminc.com

Advanced Laser Materials
www.alm-llc.com

MPF