Shapes that can be Sintered
With different types of metallurgy processes, there are different design requirements. The sintering process requires the design of sintered base parts on a number of shape recommendations. These recommendations are aimed at making the compaction of powders more feasible and minimize the cost of production.
The recommended shapes of sintered metal parts are a consequence of the following determining conditions:
The shape of the part must be designed in such a way so that the compaction tooling is robust and does not break during the process.
Basic considerations that must be taken here include:
- The avoidance of cylindrical shapes perpendicular to the direction of compaction.
- Avoiding frontal holes with a diameter of less than 1.5 mm (± 0.059 inches).
- Avoid frontal shapes that have thin edge sections.
- Avoid blind holes that are too slender as well as narrow and deep notches.
- Here, avoiding punches with thinner wall thicknesses (smaller than 1.5 mm / ± 0.059 inches) are important.
- Here, finish the front rims with flat end chamfers or cylindrical zones of 0.5 mm (± 0.0197 inches) in length.
- Avoid severe tooling transitions.
The geometry of the part must be designed in such a way as to enable ejection from both the compacting tool used in the metal sintering process as well as ejection from the sizing tool.
Considerations that should be taken into account include:
- Geometries that prevents the component from ejecting (such as lateral holes and undercuts) should be avoided.
- Introduce de-molding angles that are higher than 7°. Note that these angles can be smaller, depending on the final component.
Minimum Wall Thicknesses
In terms of design, the following considerations must be taken into account:
- Generally, a minimum wall thickness of 1.5 mm (± 0.0197 inches) is required. Not however that, in some cases, a wall thickness of up to 0.8 mm (± 0.0335 inches)is possible.
- The tool filling cavity must be wide enough as to allow for powder participles to penetrate and fill the cavity efficiently.
Integrity of the Green Part
The green part produced in the sintering process has to be strong enough to undergo processes without affecting the integrity of the part. This is also needed in order to avoid internal defects that can be caused by handling and ejection.
Here, the following considerations must be taken into account:
- Avoid sharp edges and place radii in all the tooling profiles.
- The thickness to width ratio of flanges should not be more than 5.
- Flanges should have a thickness of more than 2 mm (± 0.079 inches). Note that this thickness can, in some cases, be smaller.
- Try to finish frontal rims with the use of flat end chamfers.
While the considerations mentioned above also apply the to design of gears, the following, more specific criteria, must also be taken into account:
- Helical teeth are required to have a helix angle that is lower than 25°.
- Roots and tooth tips must have a radii that is higher than 0.25.
- The minimum modulus has to be 0.5. note however that, in some cases, 0.25 is also achievable.
Products Suitable for Metal Sintering
Because products can be manufactured to net shape or near net shape, metal sintered parts range from bearings and electrical sprockets to cutting tools and gears.
In large production volumes, bearings and gears are ideal. The reason for this is that the geometries defined are two dimensional. Another reason is that the porosity of the part is needed as it serves as a reservoir for lubricants – a requirement for these type of parts and components.
Note that the metal sintering process is unique because it is capable of producing parts with a controlled porosity – a requirement in a number of part functions such as seen with gears and bearings.
Different types of powder metallurgy, like conventional powder metallurgy, is also capable of producing parts from unusual alloys and metals. This advantage of the process also sets it above the rest, as the manufacturing of parts from unusual metals are difficult, and in some cases impossible, to produce using other manufacturing processes.
Self lubrication is also another huge aspect of different types of metallurgy processes. Because parts produced using the metal sintering process has a controlled porosity, the porosity of the material can be filled with oils, delivering a self-lubricating component.
Some examples of sintered base metal components include:
- Sintered Stainless Steel Parts
- Mechanical and Hydraulic Parts
- Self Lubricating Bearings
- Soft Magnetic Parts
Common applications for sintered gears:
- Gearboxes for various applications such as seen in household appliances, car seats, rotary roasters, automotive gearboxes, starters, drilling machines etc.
- Fluid transfer gears (such as fuel pumps, SCR pumps and oil pumps).
- Pulleys and Sprockets used for connecting systems (such as water pumps, camshafts, clutches and crankshafts).
Sintered Stainless Steel Parts
Sintered stainless steel is used in the following applications:
- SCR Pumps (such as gears, g-rotors and plates).
- Exhaust Systems (such as seen in flanges).
- Brakes (such as ABS sensor rings, vacuum pumps and rotors).
- Toothed Parts (such as seen in special gear for electric motors as well as gearboxes).
- EGR Systems (such as valve guides, cams, rods, spacers and internal and external flanges).
Mechanical and Hydraulic Parts
Here, sinter base structural components have the following applications:
- Brakes (such as couplings, ABS sensors, hubs, rotors and plates).
- Transfer Cases (such as sprockets, 4 X 4 pumps, hubs, carriers and cams).
- Shock Absorbers (such as valves, spacers, guides and pistons).
- Transmissions (such as gears, plates, levers, starters and rotors for CVT systems, forks, synchronizing hubs and fingers).
- Oil Pumps (such as stators, housings, gears and rotors).
- Steering (such as rings and plates for powder steering pumps, couplings, gears and rack guides).
- Vehicle Engines (such as pulleys, sensors, gears, forks and sprockets).
- VVT (such as spacers, stators, rotors and pulleys).
- Industrial Pumps (such as hydraulic parts and gears).
- Fuel Pumps (such as plates, counterweights, rotors, stators and g-rotors).
- Timing (such as regulation forks and rocker arms).
- Refrigerator Compressors (such as pistons, rods and counterweights).
- Safety and Comfort (components such as those used in air conditioning, doors, mirrors, safety belts, air bags, cameras and fans).
Other components manufactured with sintered base components and parts include lawn mowers, awnings, arms, trains, shutters and taps. Components are also used in agricultural and industrial machinery.
Self Lubricating Bearings
Components here are used in the following applications:
- Automotive (such as EGR systems, fuel pumps, cooling systems, steering, transmission, starters, wipers, mirrors, sunroofs etc.).
- Household Appliances (such as washing machines, juicers, coffee machines, boilers, lawn mowers, vacuum cleaners etc.).
- Industrial (such as bottling machinery, sewing machines, electrical switchgears, general assembly machinery, key duplicating machines etc.).
- Home Appliances (such as garage doors, sliding windows, hinges, swivel chairs, locks etc.).
- Linear and Rotary Actuators (such as electromagnetic, pneumatic and hydraulic actuators).
- Electric Motors and Gearboxes (both universal and customized components).
Soft Magnetic Parts
Here, soft sintered magnetic components are used in the following applications:
- Custom magnetic components (such as electric motors, pole shoes etc.).
- Sensors (for ABS brakes, crankshafts, engines and camshafts).
- Linear and rotary actuators ( such as coil cores, stators, armatures etc.).
Back to Main Page: Sintered Metal Manufacturers
Further Suggested Reading:
- Metal Sintering Process
- Metal Sintering versus Metal Injection Molding
- Materials used in Metal Sintering
- The Alternative Metal Sintering Process
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