Scope
The penetration test for investment casting waxes offers a measure of consistency of a finished wax
product. Due to differences in test methods highlighted in the procedure, the results obtained can be
helpful in reviewing the repeatability of the finished wax material, but methods used should be considered
when reviewing test results, from different suppliers of finished goods.
Summary of Method
This method describes a procedure for the determination of penetration as a measure solid investment
casting pattern wax.
The wax sample is melted into flat bottom penetration dishes and allowed to cool to ambient temperature. The solid wax sample is stabilized in a water bath for a set period. The hardness of the wax is measured in units of 0.1mm at 25 ˚C; 77 ˚F for 5 secs.
The wax sample is melted into flat bottom penetration dishes and allowed to cool to ambient temperature. The solid wax sample is stabilized in a water bath for a set period. The hardness of the wax is measured in units of 0.1mm at 25 ˚C; 77 ˚F for 5 secs.
Safety
Organic materials may be irritant or cause sensitization. Materials should not be manually handled without
gloves. Wash hands after contact.
- Work area should be free of sources of ignition.
- Hot plate is very hot and should be handled with care.
- Penetration needle is pointed and should be handled with care
- Remaining wax should be disposed of according to local disposal regulations
- Safety glasses and heat proof gloves must be always worn
- Part of this test which covers melting of the wax, should be performed in fume cupboard with face shield at appropriate height.
Equipment and Materials
- a. Flat bottom Penetration Dishes capable of holding 50 grams of wax, see Figure 1 (next page). Or the wax sample can be poured into a shouldered brass ring (as used in Ring and Ball softening method) when placed on a flat surface, to produce a smooth test surface.
- b. Penetrometer with -100 grams or 250 grams or 450 grams weights. Weight used to be confirmed on test report. See Figure 2 (next page)
- c. Penetration Needle suitable for ASTM D5 or IP49 test method or a suitable needle agreed between customer and supplier. See Figure 3 (next page)
- d. Water Bath set at 25 °C +/- 0.2 °C; 77 ˚F +/- 0.36 ˚F
- e. Hot Plate
- f. Glass stirrer rod
Equipment and Materials(Continued)
Figure 1 - Flat bottom Penetration Dishes
Figure 2 - Penetrometer
Figure 3 – Penetration Needle
Procedure
- Melt the wax sample in the penetration dish on the hot plate, ensuring the temperature of the wax sample does not exceed 90˚C; 194 ˚F.
- Remove the penetration dish from the hotplate, stir the wax to make sure all components are mixed equally.
- Allow the wax sample to cool to ambient temperature.
Figure 1 - Procedure Sequence
Procedure(Continued)
Note:
- An empty flat penetration dish
- Add the wax sample to the flat penetration dish and heat on a hotplate
- Remove melted wax material from the hotplate
- Stir to homogenize the wax material
- Allow the wax material to cool to ambient temperature
Figure 2 – Wax Cavitation
Figure-2 notes
- a. Sample with minimal cavitation
- b. Sample with significant cavitation
Procedure(Continued)
Ensure the wax sample in the penetration dish has minimal cavitation on cooling
- Place the prepared sample into the water bath, after cooling, and leave to stabilize for 2 hours, ensuring
the temperature of the water bath is at 25 ˚C; 77 ˚F.
Note: For water soluble waxes, place them in the zipped bag to avoiding direct contact with the water, then place in the water bath and leave to stabilize for 2 hours, ensuring the temperature of the water bath is at 25 ˚C; 77 ˚F - Remove the dish from the water bath and place it under the penetrometer needle, which is then lowered so that the tip just touches the wax sample.
- Move the pointer shaft down until it touches the plunger retaining screw.
- Zero the pointer on the penetrometer dial and then push the button to release the needle for 5 seconds (the use of an audible timing device is recommended).
- Release the button to re-clamp the needle and read and record the depth of penetration.
- Repeat the test twice more and report an average reading of all three results.
