investment casting vs die casting what is rapid tooling -

by:Hanway     2019-08-11
A much-The application prospect of rapid forming technology is rapid mold, automatic manufacturing of production quality machine tools.Tools are one of the slowest and most expensive steps in the manufacturing process because very high quality is required.Tools usually have complex geometry, but the dimensions must be within millimeters.In addition, the tool must be hard and worn-The surface roughness is very low (about 0.Average Root variance of 5 microns ).To meet these requirements, molds have traditionally been manufactured by CNCElectronic ProcessingDischarge processing, or manual processing.All of this is expensive and time consuming, so manufacturers want to speed up the process with fast prototyping.Peter Hilton, president of technical strategy consulting at MA Concord, believes that "tool costs and development time can be reduced by 75% or more by using fast tools and related technologies ".Fast tooling can be divided into two categories: indirect tooling and direct tooling.
Indirect tools: most quick tools today are indirect: RP parts are used as patterns for making molds and molds.
(1) vacuum casting: In the simplest and oldest rapid mold technology, the RP positive pattern is suspended in a large bucket of liquid silica gel or room temperature vulcanization (RTV) rubber.When the rubber is hardened, it is cut in half and the RP pattern is removed.The resulting rubber mold can be used to cast up to 20 polyurethane replicas of the original RP pattern.A more useful variant, called a thousand tons powder metal sintering process, produces metal tools using rubber molds.The Kiloton process, developed by 3 m and now owned by 3D Systems, includes filling rubber molds with powder tool steel and epoxy adhesives.When the adhesive is cured, remove the "green" metal tool from the rubber mold and then sintering.At this stage, the metal has only a density of 70%, so it is infiltrated by copper to approach its theoretical maximum density.These tools have a fairly good precision, but they are limited in size to less than 25 cm.
(2) sand casting: RP model is used as the positive pattern around the sand type.LOM models that are usually used similar to the traditional wooden models used for this purpose.If the seal is completed, the LOM pattern can produce about 100 Sand Shapes.
(3) Investment Casting: Some RP prototypes can be used as investment casting patterns.The pattern should not expand when heating, otherwise the ceramic shell will be cracked during the high pressure sterilization process.Both strategic and cube companies produce investment casting wax for their machines.Paper LOM prototypes can also be used because their dimensions are stable with temperature.The paper shell is burnt out, leaving some ash to be cleared.
To counter the thermal expansion in the stereo printed parts, the 3D system introduces fast casting, a architectural style with solid crust and most of the hollow internal structures.When heating, the part collapses inward.Similarly, the DTM sells real polymers, a porous substance that expands very little with increasing temperature, for SLS machines.
(4) Injection Molding: CEMCOM Research Associates, Inc.A ncc tool system has been developed for the manufacture of metal/ceramic composite molds for plastic injection molding.First, match with a stereo tablet.The plate positive pattern that needs to be formed.To form the mold, the SLA pattern is plated with nickel and then reinforced with hard ceramic material.In order to remove the pattern, the two molds are semi-separated, leaving a matching mold group that can produce thousands of injection molds.
Direct tools: making hard tools directly from CAD data is the holy grail of quick tools.There are still a few years before this can be achieved, but some significant progress is being made.
(1) Rapid tools: DTM process of selective sintering polymerWrap steel balls together to produce metal molds.The mold is then placed in the furnace where the polymer adhesive is burned and the parts are infiltrated by copper (such as the reprocessing process ).The final mold can produce up to 50,000 injection molds.
1996 Cypress 30,000 SLS on plastic tables-built mold.This is the first widely sold consumer goods to be produced through direct fast tools.In Irwin PA, Extrude Hone will soon sell a machine based on the 3D printing process that MIT produces bronzePenetrate PM tools and products.
Sandia National Laboratory and Stanford University can create metal tools from CAD data.
Stainless steel, tungsten, titanium carbide ceramics.The laser beam melts the top layer of the part in the area where the material is to be added.
Inject the powder metal into the molten pool and solidify.Add Layer after layer until the part is finished.Unlike conventional powder metal processing, the lens produces completely dense parts because the metal is melted, not just sintering.The resulting parts have excellent mechanical properties, but at present the process is only suitable for parts with simple and uniform cross sections.
Direct aiming (ACES injection molding): a technology from 3D SystemsThe produced cores are used together with traditional metal molds for injection molding of high density and low density polyethylene, polystyrene, polypropylene and ABS plastics.For less than 200 shapes, very good accuracy can be achieved.It will take a long time (5 minutes) to allow the molding to cool down to not stick to the SLA core.
In another variant, the core is made from a thin SLA housing filled with epoxy and aluminum pellets.The high conductivity of aluminum helps to cool the molding faster, thus shortening the cycle time.To improve wear resistance, metal can also be plated on the outer surface.Production operation 1000-In order to make this process economically viable, 5000 styling is envisaged.
(Month) LOMComposite;Helysis and the University of Dayton are working on the development of ceramic composites for the manufacture of laminated objects.The LOM composite parts are very sturdy and durable and can be used as tools in various manufacturing processes.
(4) sand type: there are at least two RP technologies that can build sand type directly from CAD data.DTM sells sand-Just like the material that can be sintering into the mold.Solingen uses 3DP to produce ceramic molds and cores for investment casting (direct shell production casting.
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