UNIT -6 Rapid Tooling

Copper polyamide Copper polyamide is a new metal plastic composite designed for short run tooling applications (100 to 400 parts) from common plastics. Tooling inserts are produced directly in the SLS machine with a layer thickness of 75 µm.

Subsequent finishing is necessary before their integration in the tool base. No furnace cycle is required and unfinished tool insert can be produced in a day. During the CAD stage, Copper polyamide inserts a shelled and cooling lines, ejector pin guides, gates and runners are included in the design and built directly during the SLS process.

Then the insert surface are sealed with epoxy and finished with sand paper and finally the shell inserts are packed up with a metal alloy.

Advantages Inserts produced from copper polyamide are easy to machine and finish. Heat resistant and thermal conductivity are better in most plastic tooling materials. The cycle times of moulds employing copper polyamide inserts are similar to those of metal tooling.

Direct Metal Laser Sintering

Working principle: Direct Metal Laser Sintering is an additive manufacturing process that uses a laser beam to fabricate metal parts by sintering of metal powders smeared on a substrate with recoater system.

Salient features of Direct Metal Laser Sintering Machine: Make and model: EOSINT M250 x-tended rapid prototyping machine made in Germany. Laser used is carbon dioxide which is 240 watts. Build size is 250x250x150 mm3. Metal Powder is steel , Bronze, Nickel, titanium. Surface roughness: 10 microns.

Dimensional Accuracy : -+ 100 microns. Hardness is 40-45 HRC. Porosity less than 0.5%. Tooling for plastic moulds: Tool life upto 10 lakh parts. Tooling for die casting: tool life upto 5000 parts. Layer Thickness is 0.1 mm. Laser Beam diameter is 0.4 mm. Layer thickness 20-40 microns.

Post Processing: Short peening and polishing to improve surface finish. Infiltration with high temperature epoxy resin to reduce porosity. Conventional machining, threading, milling etc.

DMLS APPLICATIONS Metal Parts Dies and Moulds New Materials Functional Testing Form and Fit Plastic Moulding Die Casting Investment Casting Rubber Moulding Metal Stamping Metal Matrix Alloys

LENS (Laser Engineering Net Shaping) OR DMD LENS is an additive manufacturing process that uses the high power laser to fabricate fully dense parts by melting metal powders feed through the nozzles.

The LENS process is unique since it goes from raw materials directly to metal parts without any secondary operations. It can produce parts in a wide range of alloys, including titanium, stainless steel, aluminum, Inconel.

The LENS uses 4 nozzles to make 3 dimensional, high density, parts and molds from the inside out. The nozzles direct a stream of metal powder in argon gas at a movable central point while a high-powered laser beam heats the point. Throughout the process, the substrate continuously moves, guided by data derived from a thin layer of a CAD solid model.

Layer by layer the nozzles and laser worked together to gradually build up the model.

Features: Make and Model: DMD 1050 5 axis rapid prototyping machine POM Incorporations USA. Laser type is diode with power of 1000W Build Size is 300x200x300 mm3. Metal Powder Stainless Steel, titanium ,cermets ,ion, super alloys. 5 axis metal deposition capability.

DMD cam software for 5 axis deposition power generation. Closed loop feedback system to monitor the layer thickness. DMD vision system for image capturing and automatic NC tool path generation. Integrated DMD data base technology for process parameters. Pyrometer for melt cool temperature measurement.

Advantages Good grain structure. Good metallurgical properties at reasonable speeds. Fully dense Parts are obtained.

DMD APPLICATIONS Conformal cooling Die Casting Plastic Injection Moulds

Hard Facing /Coating Oil Industries Wood Industries Stamping Trimming Forging

Remanufacturing Special Applications Turbine Components Large Components with large lead time Expensive Components Special Applications Lattice Structures Valve Seat Cladding

PROMETAL SYSTEMS Prometal systems are directed towards building injection tools and dies as the powder used is steel based which is durable enough to withstand high pressure and temperature. The model is built from bottom to top with layers printed in the shape of crossection of parts.

The resulting green model is then sintered and infiltrated with bronze to give the part dexterity and full density. The pro metal systems is one of the few rapid prototyping techniques to have metal material capability of 3D printing process incorporated in the pro metal system.

Prometal system hardware: Build and feed piston These pistons provide build area and supply material for constructing parts. The build piston lowers as part layers are printed while the feed piston raises to provide a layer by layer supply of new materials. This provides z-motion of the part build.

Print Gantry The printed gantry provide x,y motion of part building process. It houses print head wiper for powder landscaping and the layer drying unit. Powder overflow system The powder overflow system is an opening opposite the feed piston where excess powder scrap across the build piston is collected.

Software: The prometal starts with standard STL file format, which is imported in to the prometal software where it is sliced and placed in an orientation with the shortest z-height. This has fastest build capability like other rapid prototyping system in x-y direction. The part can be manually reoriented if necessary.

Machine Preparation for build: Check powder at the feed piston. Check whether wiper blade has landscape build area. Check binder fill and take up. Excess powder should be vacuumed away around the builder gantry. Lubricate parts of the system regularly.

Build Technique: The prometal builds parts in layer by layer fashion. The following is the general description of part build process. The bottom crossection of the part is printed on the 1st layer of the powder The jets prints in y direction as gantry moves in the printer head width increments in x direction.  

When layer is printed the gantry remains in the left side of the table while the build area piston lowers the slice thickness amount. The feed piston raises by small amount and the gantry sweeps across part bed and over flow, spreading across a new layer of powder ,with excess powder been captured in overflow.

The next layer is printed and the process is repeated until it reaches the top layer of part.

Post Processing: The following are the post processing steps for the part to be infiltrated with bronze, the typical infiltration method. Powder Removal: Excess powder must be removed by brushing, vacuuming.

Thermal cycle 1: Sintering Once powder is removed from the part it is placed in the owen and heated to a temperature high enough to burn off the polymeric binder. Thermal Cycle 2: Infiltration The part is cycled in a furnace again only this time, bronze is melted and wicked into steel skeleton until a fully dense part is created with 60% steel and 40% bronze.

Finishing: Depending on the application of the component finishing can be done with conventional machining, polishing and sanding technique to the desired quality.

Uses of Prometal: Used in manufacturing environment. Moulds are used in conventional injection moulding process as they are steel based materials. Parts are used in injection moulding extrusion dies, direct metal parts blow moulding patterns.

Advantages: Capacity to fabricate direct metal parts from the CAD data. Disadvantage: Post processing is required. Product time is long. Chances of part deformation during thermal cycle.

Direct Metal:- The capability of a RP system to fabricate components with metallic based materials

Green Form:- A soft unfinished component that requires additional heat treatment in order to achieve full strength and density