1、 WORLDWIDE ENGINEERING STANDARDS General Specification GMW16578 Acceptance Criteria for Voids in Cast Aluminum Rotors Copyright 2012 General Motors Company All Rights Reserved August 2012 Originating Department: North American Engineering Standards Page 1 of 10 1 Introduction Note: Nothing in this s
2、tandard supercedes applicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Scope. This standard defines the acceptable levels of surface porosity and internal voids in fully machined aluminum rotor cas
3、tings used in vehicles containing electric machines. 1.2 Mission/Theme. This document describes the allowable porosity limits in the cast aluminum regions of high pressure die cast rotors. It also serves as an acceptance standard for internal and surface anomalies and discontinuities. This standard
4、does not preclude the requirements of any other further refined inspection specification (example: control plan) or engineering drawing requirement as long as the minimum requirements of this standard are met or exceptions approved by General Motors. 1.3 Classification. No applicable. 1.4 Retention
5、of Test Measurements. All test measurements shall be recorded and retained per GM record retention policies. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASTM E505 2.2 GM Standards/Specifications. GMW3059 3 Re
6、quirements 3.1 General. Excessive casting defects that reduce the integrity of the casting, or adversely affect the structural soundness of the part are not acceptable. 3.2 Definition of Void. Individual pores, interconnected porosity, shrinkage, hot tears, cracks, oxide films, electrically insulate
7、d aluminum inclusions (secondary metal flow), see Figure 1, other inclusions (such as carbon and die lubricant residue) are here referred to as voids. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16578 Copyrig
8、ht 2012 General Motors Company All Rights Reserved August 2012 Page 2 of 10 Note: The inclusions are marked with gray arrows and indicate aluminum that formed during a secondary flow. The surface of the aluminum island is oxidized and therefore the island does not contribute to the electrical conduc
9、tance of the squirrel cage. Figure 1: Polished Cross-section of a Single Conducting Bar Showing an Example of Electrically Insulated Aluminum Inclusions That May Sometimes Occur in the Conducting Bars of Die Cast Rotors 3.3 Acceptance Practices. A sound casting with minimal amount of voids is expect
10、ed. Voids that are acceptable are still subject to continuous improvement requirements. Chronic voids should be reduced or eliminated by process and design improvements, process quality controls, and technology advances. Final determination of disposition of parts with voids is defined by GM Quality
11、 procedures, the same as for any other feature out of print, or in dispute. 3.4 Nondestructive Evaluation. 3.4.1 Radiographic inspection. The cast rotor end rings in their entirety shall be inspected 100% using x-ray procedures approved by GM engineering. The x-ray procedure shall be correlated to a
12、ctual porosity size and approved by GM Engineering. Acceptable level of voids in the end rings is Level 3 per ASTM E505. Level 3 is the maximum allowable level of voids in all regions of the end rings. Acceptable level of voids at the interface between end rings and conducting bars (see Figure 2) is
13、 Level 2 per ASTM E505. Any ultimate acceptance criteria shall be agreed upon between GM engineering and the supplier. For x-ray inspection schedule after capability has been demonstrated refer to the supplier quality control plan. Figure 2: Illustration of the Interface between the Conductive Bar a
14、nd the End Ring in Cross-section 3.4.2 Visual Inspection of As Cast Rotors. 100% inspection is required. Surface porosity, cracks, hot tears, inclusions, cold flow lines, blisters, handling damage, indications of die lubricant are not acceptable on as-cast surfaces including conducting bars and end
15、rings. The acceptance criteria for breakout due to the removal of gates and overflows shall be agreed upon between GM Engineering and the supplier. 3.4.3 Visual Inspection of Rotors after Machining. All machined surfaces of the rotors shall meet the surface porosity requirements defined in this stan
16、dard and the cast rotor engineering drawings. The following definitions and standard surface porosity limits (see Table 1) apply to die cast aluminum rotors after machining. 3.4.3.1 Definition of Porosity Size. Porosity size is determined by the diameter of the minimum circle that completely circums
17、cribes the pore. See Figure 3. 3.4.3.2 Definition of Max Size. Porosity is within acceptance limits for “Max Size” when a circle of the diameter of the specification limit can completely circumscribe any pore on the surface. See Figure 3. Provided by IHSNot for ResaleNo reproduction or networking pe
18、rmitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16578 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 3 of 10 3.4.3.3. Definition of Indication Size. “Indication Size” is used to count pore for “Min Spacing” “Max Density”, and “Total Indications”
19、 requirements. A pore is counted as an indication when the porosity size is larger than the “Indication Size” limit specified for that category. See Figure 3. 3.4.3.4. Definition of Min Spacing. Porosity is within acceptable limits for “Min Spacing” when the shortest line between the edges of two in
20、dications is greater than the spacing specification limit. See Figure 4. Note: Circle has diameter of 1.5 mm (no scale). Figure 3: Example of Porosity Size Limit (per Category C) or Determination of Indication (for Category F) Note: Lines are 2.0 mm apart, porosity is greater than 0.5 mm size (to ra
21、te as indication) (no scale). Figure 4: Example of Porosity Spacing Limit (per Category C) 3.4.3.5 Definition of Max Density. Porosity is within acceptable limits for “Max Density” when a square of the area of the specification limit can cover (partially or fully) no more than the number of indicati
22、ons in the density specification limit. See Figure 5. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16578 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 4 of 10 Note: Square is 161 m
23、m2, porosity is greater than 0.75 mm size (to rate as indication) (no scale). Figure 5: Example of Porosity Density Limit (per Category B) 3.4.3.6 Depth. The depth of the surface porosity is measured with an appropriate depth gage. 3.4.3.7 Definition of total indications. Surface porosity is within
24、acceptable limits for “Total Indications” when the total quantity of pores that can be rated as indications does not exceed the total indications specification limit. See Figure 6. Note: Box is entire restricted surface, porosity is greater than 0.75 mm in size (no rate as indication) (no scale). Fi
25、gure 6: Example of Total Indications Limit (3 = Acceptable, 4 = Not Acceptable) Table 1: Standard Surface Porosity Limits Category (units) Maximum Size (mm) Indication Size (mm) Minimum Spacing (mm) Maximum Density (indications/mm) Depth (mm) Total Indications (indications) A 0.5 0 3 20/161 1.0 - B
26、1.0 0.5 2 5/161 2.0 - C 2.0 1.0 2 4/161 4.0 - D 3.0 1.0 4 3/161 4.0 - E 4.0 1.0 4 3/161 4.0 - F 5.0 1.5 4 3/161 4.0 - G Note 1 1.0 wide x 2.5 long 1.0 4 3/161 2.0 - Note 1: In category G, the max size of the allowable porosity is a rectangular shape 1.0 mm in width (axially) and 2.5 mm long (circumf
27、erentially), in respect to the primary axis of the part. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16578 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 5 of 10 3.4.4 Surface Poro
28、sity Limits for High Pressure Die Cast Aluminum Rotors after Machining. It is anticipated that cast rotor technology will continue to evolve after the release of this standard. As a result, porosity requirements for machined surfaces of castings may require new or varying porosity limits. The intent
29、 of this paragraph is to allow for the creation of porosity allowances outside of Table 1. Such surface porosity callouts shall be agreed upon between General Motors and the supplier. 3.4.5 Inspection with Automated Rotor Quality Analyzer (RQA). The quality of rotor bars shall be inspected using an
30、automated RQA. The bar quality inspection procedure shall be agreed upon between GM Engineering and the supplier. For test schedule refer to the supplier quality control plan. 3.5 Destructive Evaluation. Destructive evaluation of aluminum rotor bars shall be conducted on rotors free of OD flash. OD
31、flash may be created during the casting process and should be removed before any destructive evaluation. The frequency of testing and lot size shall be agreed upon between the supplier and GM Engineering and specified in the supplier quality control plan. 3.5.1 Load-to-Failure Tensile Tests. 3.5.1.1
32、 Sample Preparation. Load-to-failure tensile tests shall be performed on double conducting bar sections of the rotors, see Appendix A. The double conducting bar sections to be tested shall be agreed upon by GM Engineering and the supplier. The selection of the bar sections for testing shall be based
33、 upon high speed metal flow simulation results as described in the corresponding statement of requirements (SOR). The sample preparation shall be approved by GM Materials Engineering. 3.5.1.2 Load-to-failure Test Procedure. The test procedure and test facilities shall be approved by GM Materials Eng
34、ineering. 3.5.1.3 Acceptance Criteria. The double conducting bar samples shall be pulled in tension until separation. The cross-sectional area of an individual conducting bar (A, mm2) shall be determined from the rotor lamination drawing. Bar sets shall achieve a minimum of 50 MPa tensile stress bas
35、ed on the area of the two conducting bars (2A, mm2). If the minimum required tensile stress of 50 MPa is not achieved the supplier shall notify GM supplier quality engineering. The supplier shall determine the cause of the low pull loads and implement corrective actions per GM-approved supplier cont
36、rol plan. 3.5.2 Void Area Evaluation. 3.5.2.1 Sample Selection and Preparation. This test shall be performed only on double conducting bar sections that have already met the load-to-failure acceptance limit of 50 MPa. Each bar fracture surface (four fracture surfaces per bar set) after load-to-failu
37、re test shall be evaluated for excessive void area with a stereo microscope and reviewed with GM Engineering. Void area is considered excessive when it is greater than 5% of the total fracture surface. The fracture surface with the greatest void area per bar set shall be selected for void area evalu
38、ation. The selected fracture surface shall be sectioned not more than 3 mm below the base of fracture surface and the specimen shall be polished following standard metallographic procedures. Care shall be taken not to smear, scratch or embed polishing media in the polished surface. The initial polis
39、hed surfaces shall be evaluated by GM Materials Engineering for approval of the polishing procedure. 3.5.2.2 Void Area Measurement. See Appendix B. 3.5.2.3 Acceptance Criteria. Determine the total amount of void cross-sectional area as a percentage of the individual bar cross-sectional area. The max
40、imum amount of acceptable voids as a fraction of the bar cross-sectional area is 5%. The procedure for area void evaluation shall be approved by GM Materials Engineering. If the maximum allowable void area limit is exceeded the supplier shall notify GM supplier quality engineering. The supplier shal
41、l determine the cause of the high percentage of porosity and implement corrective actions per GM-approved supplier control plan. 4 Validation 4.1 General. Not applicable. 4.2 Validation Cross Reference Index. Not applicable. 4.3 Supporting Paragraphs. Not applicable. 5 Provisions for Shipping Not ap
42、plicable. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16578 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 6 of 10 6 Notes 6.1 Glossary. Voids: Individual pores, interconnected por
43、osity, shrinkage, hot tears, cracks, oxide films, electrically insulated aluminum inclusions (secondary metal flow), see Figure 1, other inclusions (such as carbon and die lubricant residue). Load-to-Failure Test: Axial tensile pull test of double bar rotor sections gripped at the rotor end ring. Vo
44、id Area Evaluation: Images analysis used to determine the ratio of total void area in respect to total bar area shown on engineering drawing. 6.2 Acronyms, Abbreviations, and Symbols. A Cross-sectional area of rotor conducting bar in mm2 RQA Rotor Quality Analyzer SOR Statement of Requirements 7 Add
45、itional Paragraphs 7.1 All parts or systems supplied to this standard must comply with the requirements of GMW3059, Restricted and Reportable Substances for Parts. 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: GMW16578 9 Release and Revisions This
46、standard was originated in March 2011. It was first approved by the Non Ferrous Metals GSSLT in August 2012. It was first published in August 2012. Issue Publication Date Description (Organization) 1 AUG 2012 Initial publication. Provided by IHSNot for ResaleNo reproduction or networking permitted w
47、ithout license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16578 Copyright 2012 General Motors Company All Rights Reserved August 2012 Page 7 of 10 Appendix A: Sampling for Load-to-Failure Test A1 Bar Position Indicator It is critical to have a consistent rotor orientation in the die and cond
48、ucting bar number traceability. This is accomplished by applying a bar position indicator (mark) in the cast tool which results in a mark on every rotor produced following the engineering drawing, see Figure A1. The rotor bars are numbered based on the bar position indicator and this bar numbering c
49、orresponds to the bar numbering used in the simulation model. The cast bar indicator position, bar numbering, and the simulation software shall be agreed upon between GM engineering and the supplier. Figure A1: Example of A Cast Bar Indicator A2 Excising of Double Conducting Bars The bar sections approved for testing shall be identified and marked on the rotor casting, as shown in Figure A2. The bar se
