BS ISO 28279:2010 pdf free download Sintered metal materials — Determination of the level of cleanliness of powder- metallurgy parts
This International Standard specifies the determination of the amount and nature of the surface contamination of powder-metallurgy (PM) parts (i.e. the level of cleanliness of PM parts).
2 Symbols and units
For the purposes of this document, the following symbols and units apply.
Symbol Explanation Unit
C Amount of contaminant. mg/part
m 1 Mass of the as-received, dried 5 µm filter (4.4). g
m
m 2 Mass of the dried 5 µm filter (4.4) plus the contaminants. g
N Number of parts taken for testing. —
3 Principle
PM parts are pressure-rinsed with a filtered solvent that is subsequently re-filtered in order to capture surface contaminants. The filtered residue is weighed and the contaminant particles are examined with a magnifying
glass or stereomicroscope in order to determine their nature.
4 Apparatus
4.1 Filter funnel.
4.2 Filtering flask, with a minimum volume of 2 L.
4.3 Vacuum pump.
4.4 Filter, 5 µm, made of polyester (preferred material) or polyamide of diameter 20 mm to 50 mm (type of filter depending on the solvent).
4.5 Filter, maximum 1 µm, made of polyester (preferred material), polyamide or cellulose (type of filter material depending on the solvent) of diameter 20 mm to 50 mm.
4.6 Analytical balance, of capacity at least 20 g and 0,000 1 g accuracy.
4.7 Petri-dish set, (only the bottom portion).
4.8 Drying oven, with a capability of at least 1 00 °C and 1 0 °C accuracy.
4.9 Desiccator.
4.10 Pressure gun for liquids.
4.11 Solvent (white spirit).
4.12 Stereomicroscope (at least ×1 0 magnification) or microscope.
4.13 Glass microscope slides.
4.14 Stainless-steel tongs, with flat tips.
4.15 Gloves, made of latex or another type of plastic depending on the solvent used. The gloves should be used in order to prevent contamination during handling.
5 Procedure
5.1 Place the 5 µm filter (4.4) on the Petri dish (see Figure 1 ), and dry it in an oven (4.8) at 1 00 °C for at least 30 min.
The recommended filter mesh is 5 µm and other mesh should be agreed between the user and supplier.
5.2 Transfer the Petri dish and filter to the desiccator (4.9), and cool it to room temperature.
5.3 Weigh the dried filter to the nearest 0,000 1 g with an analytical balance (4.6), and record the mass m 1 .
5.4 Filter at least 2 L of white spirit solvent by using the filtering flask and the vacuum pump (see Figure 2),with the maximum 1 µm filter (4.5) (see Figure 2). Keep this filtered solvent in a clean glass bottle previously cleaned with pure solvent.
The recommended solvent is white spirit and any other solvent should be agreed between the user and supplier.
5.5 Take a number of parts so as to have a total surface area of at least 1 000 cm 2 , and note the total number of parts N. Take care not to contaminate the PM parts during handling. In case of difficulty in reaching 1 000 cm 2 of surface because the part is too big or too small, the surface area should be agreed between the user and supplier.
5.6 Rinse the parts with the pressure gun (4.1 0) by using 1 L of filtered solvent, at a pressure of (200 ± 50) kPa, and save the solvent after rinsing. Ensure that the solvent wets all surfaces of the PM parts during this operation. NOTE Both parties can decide if a pressure gun should be used. In some cases, an extraction technique based on ultrasound might be suitable.
5.7 Filter the contaminated solvent by using the glass filtering flask (4.2) and the vacuum pump (4.3) using the same system as shown in Figure 2, with the previously dried and weighed 5 µm filter (4.4). The filter now has collected the contaminants from the PM parts.
5.8 Using the same vacuum system, rinse the residues and the 5 µm filter (4.4) with 200 ml of clean, filtered solvent (4.11 ) in order to remove any trapped oil.
5.9 Place the filter with residues on the Petri dish (4.7) and dry it in the oven (4.8) at 1 00 °C for at least 30 min (same system as shown in Figure 1 ). Then transfer the Petri dish and filter to the desiccator (4.9), and cool to room temperature.