1、 FORD LABORATORY TEST METHOD CA 105-01 Date Action Revisions 2001 04 30 Revised Editorial no technical change A. Cockman 1993 12 10 Printed copies are uncontrolled Page 1 of 3 Copyright 2001, Ford Global Technologies, Inc. DETERMINATION OF SURFACE POROSITY OF CASTINGS Application This method determi
2、nes the amount of surface porosity in castings and provides a rating system for acceptance. The intention of this method is to provide a common approach to the definition and quantification of surface porosity. Where surface porosity is inherent in castings produced to good commercial practice, comp
3、onent engineers have the opportunity to designate a maximum level of surface porosity against which the acceptance of the component may be made. This method thus becomes an extension of the component drawing. The definitions of porosity type, size and distribution are based on an examination practic
4、e consistent with production plant inspection viewing capabilities. These capabilities shall include the ability to examine component surfaces at a nominal 2 times magnification under good uniform illumination conditions, and with access to nominal 10 times magnification for critical applications. I
5、t should be clearly noted that the ability to assess surface porosity is directly related to the as-cast or machined surface finish at the point of examination. Rougher textures, particularly related to soft ductile materials, e.g. aluminum, will tend to hide underlying porosity that would have been
6、 evident on a non-distorted surface. In circumstances where classification is not possible, modifying notes by component engineering take precedence. For practical convenience, porosity is defined here as gas or shrinkage porosity. Gas porosity, either from solution or mould reaction, takes a regula
7、r, often spheroidal form typified by clean, smooth peripheries. A 2 dimensional surface assessment can give some indication of depth. Shrinkage porosity arising from compositional effects, feeding, temperature and solidification, is typified by irregular profiles resulting from interdentritic forms.
8、 Surface assessment provides limited information concerning depth. Pits, pores and voids produced for reasons other than porosity may nevertheless reveal observations similar to that of the previously described casting porosity. The pits may occur due to pluck-out on machining, slag or dross cavitie
9、s. Such features will be considered equivalent in significance to the above features in the context of surface porosity. FORD LABORATORY TEST METHOD CA 105-01 Page 2 of 3 Copyright 2001, Ford Global Technologies, Inc. Evaluation Rating Note: It is anticipated that the FLTM CA 105-01 rating designati
10、on shown on the component drawing will be supplemented by actual component parts which exhibit the acceptable porosity criteria, as agreed by Component and Manufacturing Engineering. These components, or permanent records of these components, shall be retained as master acceptance criteria for the d
11、uration of the production of these components. The porosity potential sizes, distances apart and distribution are rationalized into the following classification (dimensions in mm): Note: Diameter refers to maximum axis. GRADE SIZE MINIMUM DISTANCE BETWEEN POROSITIES (Diameter (Distribution (Distribu
12、tion (Distribution of Porosity) “L“ - light) “M“ - Medium) “H“ - Heavy) A 0 0 0 0 B 0.2 2.0 1.0 0.4 C 0.5 5.0 2.5 1.0 D 1.0 10.0 5.0 2.0 E 1.5 15.0 7.5 3.0 F 2.0 20.0 10.0 4.0 G 2.5 25.0 12.5 5.0 H 5.0 50.0 25.0 10.0 Distance between porosity and component edge to be the same as the specified diamet
13、er of porosity except for gasket sealing areas when distance between porosity and component edge shall be the same as between porosities. Example The component engineer shall specify the areas where porosity is allowed using a format of GRADE, DISTRIBUTION, QUANTITY (optional) e.g., CM10 refers to 0
14、5 mm maximum pore diameter at 2.5 mm minimum distance apart with no more than 10 pores in the designated area. If appropriate, a combination of different grades and distribution may be specified (e.g., CM10 and FL2). FORD LABORATORY TEST METHOD CA 105-01 Page 3 of 3 Copyright 2001, Ford Global Tech
15、nologies, Inc. Acceptance Criteria (unless otherwise specified on engineering drawing) In addition to the noted level of acceptable porosity shown on the appropriate component drawing, the presence of porosity at the finished component surface shall be permitted only when that porosity is free from
16、entrapped debris and loosely adhering parent metal. Pits, pores and voids containing abrasive particles (e.g., sand, swarf) are considered undesirable on critical surfaces particularly moving surfaces such as bearings or surfaces in contact with moving fluids, and are unacceptable without prior Engi
17、neering approval. In bolt bosses and threaded areas, no porosity is permitted except as designated on print on the first 3 active threads. The presence of porosity exceeding a quarter the width of a seal surface or resulting in leakage shall not be accepted. Surface porosity acceptable on thin walls
18、 shall not be opposed by porosity on the wall rear face within a distance of 25 mm. Porosity depth shall not exceed one and a half times the specified maximum diameter. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities.
