Posted tagged ‘Tool’

FINISHING OPERATIONS

August 23, 2011

Sizing:

Repressing the sintered component in a die to meet required tolerances.

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Coining:

Repressing the sintered component in a die to increase the density and to give additional strength.

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Infiltration:

Filling the pores of sintered product with molten metal to improve the physical properties.

Impregnation:

Filling of Oil, Grease or other Lubricants in a Sintered components such as Porous Heating

Machining:


Removing excess material by using cutting tool to imparts specific features such as Threads, Grooves, Undercuts etc, which are not practicable in powder metallurgy process.

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Heat Treatment:

Process of Heating & Cooling at a desired rate to improve Grain Structure, Strength & Hardness.

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Plating:

Used for obtaining Resistance to Corrosion or better appearance.

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Powder metallurgy is used in the following industries:

  • Automotive (Brake pads, Gear parts, Connecting rods, Planetary carriers, Sintered Engine Bearings);

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  • Aerospace (Light weight Aluminum base structural materials, High temperature Composite materials);

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  • Cutting tools (Hard metals, Diamond containing materials);

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  • Medicine (Dental implants, Surgical instruments);

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  • Abrasives (Grinding and Polishing wheels and Discs);
  • Electrical, Electronic and Computer parts (Permanent magnets, Electrical contacts).

 

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PRESSURE FORMING

August 22, 2011

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Material & Description

ABS

Good general purpose material, very tough yet very hard and rigid, good impact and electrical. Available in gauges from .040 to .475 with several extruded textures. Comes opaque and can be matched in custom colors.

ABS/PC

A blend or alloy of ABS and polycarbonate that thermoforms well, weathers well, good color retention, very hard, excellent impact.

ABS/PVC

Flame retardant, tough.

Acrylic

Outstanding weather resistance, excellent optics and electrical properties, poor impact, high gloss and deep luster. Available in standard gauges from .080 to over 1″. Available in clear, transparent and opaque colors.

Acrylic, cell cast

Excellent optics and hot strength, more expensive. Acrylic, continuous and extrusion cast.
Large volume use and best price, good optics.

Acrylic film

3 or 6 mil film for laminating, decorating, and weathering of extruded ABS.

DR Acrylic

Modified acrylic with higher impact properties.

Acrylic/PVC

A blend of acrylic and PVC that is a tough, chemical-resistant material that weathers well and is flame resistant. Available in custom colors.

HDPE (high-density polyethylene)

Crystalline, very tough materials, good weather resistance with UV inhibitors, resistant to many chemicals. Available in standard gauges from .040 to .500. Available in opaque custom colors. Tough and stiff. Good low temperature. Economical.

HMWPE (high molecular weight)

Excellent environmental stress crack properties, thermoforms well, good low temperature.

HIPS (high impact polystyrene)

Good general-purpose material, rigid. Available in clear but usually opaque custom colors from .030 to .350, low cost.

PVC (vinyl)

Good general-purpose material, good abrasion and chemical resistance. Available in clear but usually opaque custom colors from .030 to .125.

Expanded PVC

Stiff, light, flat, thermoformable. Available in stock colors and gauges, generally 3 and 6 mm but others also available.

PETG

Clear, higher impact than acrylic, easy to form. Available in gauges from .030 to .500.

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Pressure Forming:

Pressure Forming is the method used to produce injection mold quality, high definition plastic component parts, housings and containers without the huge expense of tooling. It involves positive pressure to force the heated plastic into the mold cavity. This is called pressure thermoforming or blow forming

Pressure Forming Working Operation:

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The highly versatile pressure forming process utilizes air pressure, from 20 to 150 psi, to force the heated sheet into a temperature controlled mold cavity. Vent holes are provided in the mold to exhaust the trapped air. The final part features sharp definition of intricate contours and tight radii. Textures and accurate details are built right into the tooling. Low-cost, highly aesthetic plastic parts of varying sizes are possible due to the application of air pressure, as well as more sophisticated process controls that better monitor tool and sheet temperatures while controlling material shrinkage during forming.

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Types Of Molding operation:

  • Positive Mold
  • Negative Mold

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Negative molds  have concave cavities. A positive mold has a convex shape.

Pressure Forming over Thermo Forming:

The basic advantage of Pressure Forming over Thermo forming is the cost advantage for small production items. The mould cost for thermo forming is considerably higher in comparison to pressure forming thus for a lower quantity precision job the best suitable method used is pressure forming.

Application:

Pressure forming is used to create in a wide array of plastic products used for packaging of food trays, blisters, covers, internal parts, housings equipment, bezels, bases, and spare parts for use in business machines, electronics, computers and peripherals, bio-medical applications, and instruments.

Features:

Pressure forming achieves features beyond the capabilities of vacuum forming including louvers, ribs, recessed areas, crisp details and logos.

Pressure forming is ideal for small to medium sized production runs that do not justify the high cost of injection molding dies. Additionally, because the aluminum tooling used in pressure forming has an unlimited lifecycle, due to the non-abrasive process versus injection, it saves a great deal of money over many years of continued use. Pressure form tooling usually costs less than 10% the cost of an injection tool. There is also a significant time savings (sometimes 25%) in tooling lead time. Sheet gauges .020″ – .500″ are capable of being pressure formed.

METALLURGY INTERVIEW

August 22, 2011

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  • What is the composition of Grey cast iron Grade 20?

Carbon      : 3.10 – 3.25%         Silicon : 1.75-1.95%    Manganese : 0.50 – 0.7%Sulphur : 0.05 – 0.07%       Phosporous : 0.04 – 0.07%

  • What is the composition of Cast iron Grade 35?

Carbon=2.90-3.10%Manganese=0.60-1.00%Silicon=1.50-1.90%Sulphur=0.10%

Phosphorus=0.15%  Chromium=0.30%        Molybdenum=0.30%   Cupper=0.25%

  • What are the super alloys?

Super alloys is an alloy that exhibits excellent mechanical strength and creep resistance at high temperatures, having good surface finish.

  • Why the Super alloys used for land-based turbines?

Super alloys are the top most alloys used for their excellent strength and corrosion resistance as well as oxidation resistance. No other alloys can compete with these grade.

  • What kinds of NDT methods are available?

1.Visual Inspection

2.Microscopy inspection

3.Radiography Test

4.Dye Penetrate technique

5.Ultrasonic testing

6.Magnetic Particle inspection

7.Eddy Current technology

8.Acoustic Emission

9. Thermograph

10.Replica Metallographic

  • What is Stress Corrosion cracking?

Stress corrosion cracking (SCC) is a process involving the initiation of cracks and their propagation, possibly up to complete failure of a component, due to the combined action of tensile mechanical loading and a corrosive medium.

  • What is meant by D2 Material used for Die tooling?

 

D2 – High Carbon Cold Work Tool Steel

D2 is a high Carbon, high Chromium, Molybdenum, Vanadium, Air hardening alloy tool steel which offers good wear resistance, high surface hardness, through hardening properties, dimensional stability and high resistance to tempering effect. D2 tool steel is also suitable for vacuum hardening.

Typical Composition

C.-1.50%

Si.-0.30%

Cr. -12.00%

Mo. -0.80%

V. -0.90%

  • What is Vacuum Induction Melting?

As the name suggests, the process involves melting of a metal under vacuum conditions. Electromagnetic induction is used as the energy source for melting the metal.

Induction melting works by inducing electrical eddy currents in the metal. The source is the induction coil which carries an alternating current. The eddy currents heat and eventually melt the charge