| CALL: 603.889.5422 |

(dick@castingreps.com)
PO Box 164, Hudson, NH 03051
Fax: 603.881.9402

Technical Chart | R.F.Q.

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ZA 12 Permanent Mold

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Spec Chart

About Us

The Plaster Mold Process
What is it?

Aluminum Plaster Mold Casting

Briefly stated, this is a method of producing aluminum or zinc castings by pouring liquid metal into plaster (gypsum) molds.

Model

Negatives and Model

Foundry Pattern Equipment

Pouring Plaster

Pouring Metal Casting

Finished Casting

Step 1 Model or Master Pattern

1. This is made from customer drawing or CAD file

2. Stereolithography, traditional hand crafted or machined

3. Model is engineered to include:
- Metal shrinkage
- Mold taper-if required
- Machine stock-if required

4. We can “clone" or adapt customer supplied model if requested.

Step 2 Foundry Pattern Equipment

1. Negative molds are made from model

2. Core plugs are made from negative molds

3. A positive resin cope and drag pattern is now made from the negative molds

4. Core boxes are made from the core plugs

5. Gating, runner system and flasks are added as necessary

6.Duplicate sets of tooling can be made from the master negative

Step 3 Plaster Mold

1. A liquid plaster slurry is poured around the cope and drag pattern and into the core boxes

2. The plaster mold is next removed from the cope and drag patterns

3. The plaster mold and cores are then baked to remove moisture

Step 4 Pour Casting

1. Molten metal is prepared by degassing and a spectrographic sample is taken to check the chemical analysis

2. The molten metal is then poured into the assembled plaster mold

3. The plaster is removed by mechanical knock-out and high pressure waterjet

4. When the casting has cooled. The gates and risers are then removed.

Step 5 Secondary Operations

1. The raw castings are inspected and serialized

2. Flash and excess metal is removed (snagged)

3. Castings may then require (per customer specification):
-Heat Treatment
-X-Ray
-Penetrant Inspection

After finish inspection, casting is ready for:
-Machining
-Chemical film, chromate conversion, paint of special finishes
-Assembly

TECHNICAL INFORMATION

The Plaster Mold Process for Metal Casting

How, When and Why To Use It

To produce precision and premium quality aluminum and zinc castings
For aesthetic applications where appearance is critical
Prototyping – to assist engineering in debugging design before committing to hard tooling
For low volume applications where quantities do not justify die cast tooling
For high volume applications of complex or unusual shapes
For castings with thin walls or where weight is critical
To simulate die castings for prototype and pilot production
Tooling is low cost and allows ease of modification
To reduce “time to market” on new programs and evaluate market potential
To reduce time for machining and secondary operations
To fill the gap if dies are lost, damaged, or delayed
To assist and reduce time for U.L. approval

Design and Technical Information

SIZE
No limitation but best range within 2” cube to 36” cube

FINISH
Can hold 63 micro-inch but normally 90 micro-inch

SHAPE
Considerable design freedom for unusual and complex shapes

WALL THICKNESS
Thin Wall .030” - .060”
Average .080” - .120”

GENERAL TOLERANCES
0” – 2” ± .010           2” – 3” ± .012
3” – 6” ± .015           6” – 12” ± .020
12” – 18” ± .030      18” – 30” ± .040
Tighter tolerances can be negotiated

LIMITATIONS
The process is limited to non-ferrous metals with pouring temperatures below 2,000” F-this includes all aluminum, zinc casting alloys and some copper based alloys.

HOLES
Not economical to cast small holes ¼” or less unless odd shapes or inaccessible areas for machining.

ALLOYS
All aluminum and zinc casting alloys to the commercial and military specifications. See separate technical sheet.

DRAFT
Typically ½” to 2 ۫
Zero draft is possible in specified areas.

Corner radii and fillets as required, type. 1/16” R.

MECHANICAL PROPERTIES
Tensile-Yield-Elongation – as per the appropriate com-metrical and "military specifications"

TOOLING-PATTERN EQUIPMENT

Loose Pattern – to expedite for up to 20 pieces

Epoxy Resin – usually up to 500 pieces

Metal – Aluminum or Brass – Used to obtain best tolerances and quality

Rubber – for quantities up to 1,000 pieces. Tooling can be duplicated easily from master tooling to expedite delivery or for higher volumes

COST
Rule of thumb for complex shapes in 15” cube
Range: Tooling – 10% of die cast tools
Place Piece Price – 10 times die casting price

DELIVERY
1-2 weeks for simple parts
6-8 weeks for complex parts

TYPICAL APPLICATIONS

Castings for telecommunications, business machines, medical equipment, computers, automotive, aerospace, electronics, robotics.

Molds for plastics industry-rotational molds, vacuum form, expanded polystyrene molds, kirksite injection molds.

Plaster and Sand Molding Combination

For castings requiring high metallurgical integrity verified by radiographic and fluorescent penetrate inspection. When used in combination with no bake sand molds the properties of plaster mold castings can be enhanced considerably talking advantage of the faster cooling rates inherent in sand molds in combination with the insulating aspect of plaster molds.

Mr. Palmer may be reached by calling toll free: 888.494.0414 or email: (dick@castingreps.com)

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Investment Casting, Lost Wax Casting, Ferrous and Non Ferrous Materials, Precision Casting, Stainless Steel, Brass, Bronze, Copper, Sand Casting, Die Casting, Plaster Mold Casting, Permanent Mold Casting, Graphite Mold Castings, Machining Services, Overseas Manufacturing Source, Investment Casting Method, Aluminum Investment Castings, Investment Casting Companies, Investment Casting Suppliers, Wax Injection, New England

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The Plaster Mold Process What is it?

Aluminum Plaster Mold Casting

The Plaster Mold Process
What is it?