ASTM B252-92(2014)

Standard Guide for Preparation of Zinc Alloy Die Castings for Electroplating and Conversion Coatings

SIGNIFICANCE AND USE
4.1 The performance and quality of electroplated or conversion-coated zinc alloy die casting depends upon the surface cleanliness and condition. Various metals are electroplated or conversion coatings are established on zinc alloys for decorative or engineering finish. The common electroplates applied are usually copper, nickel, and chromium for decorative and functional uses. The common conversion coatings applied are phosphates, chromates, and anodized coatings. Electroplated zinc die castings and conversion coatings on zinc die castings are used in many industries such as the marine, automotive, plumbing fixtures, and appliance industries.
SCOPE
1.1 This guide is intended as an aid in establishing and maintaining a procedure for preparing zinc alloy die castings for electroplating and conversion coatings. It is primarily intended for the preparation of Alloys UNS Z33521 (AG-40A) and UNS Z35530 (AC-41A) (Specification B86) for electroplating with copper, nickel, and chromium (Specification B456).  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Oct-2014
• ICS: 77.150.60 - Lead, zinc and tin products
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.02 - Pre Treatment

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: B252 − 92 (Reapproved 2014) Endorsed by American
Electroplaters’ Society
Endorsed by National
Association of Metal Finishers
Standard Guide for
Preparation of Zinc Alloy Die Castings for Electroplating
1
and Conversion Coatings
This standard is issued under the fixed designation B252; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Summary of Practice
3.1 The normal sequence of preparation steps is as follows:
1.1 This guide is intended as an aid in establishing and
(1) smoothing of parting lines; (2) smoothing of rough or
maintaining a procedure for preparing zinc alloy die castings
defective surfaces, if necessary; (3) buffing, if necessary; (4)
for electroplating and conversion coatings. It is primarily
precleaning and rinsing; (5) alkaline electrocleaning and rins-
intended for the preparation ofAlloys UNS Z33521 (AG-40A)
ing; (6) acid dipping and rinsing; and (7) copper striking.
and UNS Z35530 (AC-41A) (Specification B86) for electro-
plating with copper, nickel, and chromium (Specification
4. Significance and Use
B456).
4.1 The performance and quality of electroplated or
1.2 The values stated in SI units are to be regarded as
conversion-coated zinc alloy die casting depends upon the
standard. No other units of measurement are included in this
surface cleanliness and condition. Various metals are electro-
standard.
plated or conversion coatings are established on zinc alloys for
1.3 This standard does not purport to address all of the decorative or engineering finish. The common electroplates
applied are usually copper, nickel, and chromium for decora-
safety concerns, if any, associated with its use. It is the
tive and functional uses. The common conversion coatings
responsibility of the user of this standard to establish appro-
applied are phosphates, chromates, and anodized coatings.
priate safety and health practices and determine the applica-
Electroplated zinc die castings and conversion coatings on zinc
bility of regulatory limitations prior to use.
die castings are used in many industries such as the marine,
automotive, plumbing fixtures, and appliance industries.
2. Referenced Documents
2
2.1 ASTM Standards:
5. Composition and Characteristics of Zinc Alloy Die
B6 Specification for Zinc
Castings
B86 Specification for Zinc and Zinc-Aluminum (ZA) Alloy
5.1 The alloys used in the manufacture of zinc alloy die
Foundry and Die Castings
castings are made with special high-grade zinc conforming to
B456 Specification for Electrodeposited Coatings of Copper
Specification B6, alloyed with about 4 % of aluminum, 0.04 %
Plus Nickel Plus Chromium and Nickel Plus Chromium
of magnesium, and either 0.25 (max) or 1.0 % copper (Alloys
2.2 Military Standard:
UNS Z33521 and UNS Z35530). Impurities such as lead,
3
MIL-S-13165C Shot Peening of Metal Parts
cadmium, tin, and iron are held at or below the specified low
levels in Specification B86.
5.2 Die castings made of Alloys UNS 233521 and UNS
1
This guide is under the jurisdiction of ASTM Committee B08 on Metallic and
235530 are usually dense and fine grained but do not always
Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 on Pre
have smooth surfaces. Defects sometimes encountered in the
Treatment.
surfacelayersincludecracks,crevices(coldshut),skinblisters,
Current edition approved Nov. 1, 2014. Published November 2014. Originally
approved in 1951. Last previous edition approved in 2009 as B252 – 92 (2009).
and hemispherical pores. Burrs are usually left at parting lines
DOI: 10.1520/B0252-92R14.
where fins and gates are removed by die trimming.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
5.3 Cast surfaces are frequently contaminated with parting
Standards volume information, refer to the standard’s Document Summary page on
compounds applied at frequent intervals to die surfaces to
the ASTM website.
3
facilitate the ejection of the castings and with water-soluble
AvailablefromStandardizationDocumentsOrderDesk,Bldg.4SectionD,700
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS. oils added to quenching tanks for corrosion inhibition.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
B252 − 92 (2014)
5.4 Zinc alloy die castings are chemically active and are conveyor through successive belts or wheels to polish different
dissolvedoretchedduringprolongedcontactwithconcentrated areas,aman
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B252 − 92 (Reapproved 2009) B252 − 92 (Reapproved 2014) Endorsed by American
Electroplaters’ Society
Endorsed by National
Association of Metal Finishers
Standard Guide for
Preparation of Zinc Alloy Die Castings for Electroplating
1
and Conversion Coatings
This standard is issued under the fixed designation B252; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide is intended as an aid in establishing and maintaining a procedure for preparing zinc alloy die castings for
electroplating and conversion coatings. It is primarily intended for the preparation of Alloys UNS Z33521 (AG-40A) and UNS
B86) for electroplating with copper, nickel, and chromium (Specification B456).
Z35530 (AC-41A) (Specification
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
B6 Specification for Zinc
B86 Specification for Zinc and Zinc-Aluminum (ZA) Alloy Foundry and Die Castings
B456 Specification for Electrodeposited Coatings of Copper Plus Nickel Plus Chromium and Nickel Plus Chromium
2.2 Military Standard:
3
MIL-S-13165C Shot Peening of Metal Parts
3. Summary of Practice
3.1 The normal sequence of preparation steps is as follows: (1) smoothing of parting lines; (2) smoothing of rough or defective
surfaces, if necessary; (3) buffing, if necessary; (4) precleaning and rinsing; (5) alkaline electrocleaning and rinsing; (6) acid
dipping and rinsing; and (7) copper striking.
4. Significance and Use
4.1 The performance and quality of electroplated or conversion-coated zinc alloy die casting depends upon the surface
cleanliness and condition. Various metals are electroplated or conversion coatings are established on zinc alloys for decorative or
engineering finish. The common electroplates applied are usually copper, nickel, and chromium for decorative and functional uses.
The common conversion coatings applied are phosphates, chromates, and anodized coatings. Electroplated zinc die castings and
conversion coatings on zinc die castings are used in many industries such as the marine, automotive, plumbing fixtures, and
appliance industries.
1
This guide is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 on Pre
Treatment.
Current edition approved Sept. 1, 2009Nov. 1, 2014. Published December 2009November 2014. Originally approved in 1951. Last previous edition approved in 20042009
as B252 – 92 (2004).(2009). DOI: 10.1520/B0252-92R09.10.1520/B0252-92R14.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
B252 − 92 (2014)
5. Composition and Characteristics of Zinc Alloy Die Castings
5.1 The alloys used in the manufacture of zinc alloy die castings are made with special high-grade zinc conforming to
Specification B6, alloyed with about 4 % of aluminum, 0.04 % of magnesium, and either 0.25 (max) or 1.0 % copper (Alloys UNS
Z33521 and UNS Z35530). Impurities such as lead, cadmium, tin, and iron are held at or below the specified low levels in
Specification B86.
5.2 Die castings made of Alloys UNS 233521 and UNS 235530 are usually dense and fine grained but do not always have
smooth surfaces. Defects sometimes encountered in the surface layers include cracks, crevices (cold shut), skin blisters, and
hemispherical pores. Burrs are usually left at parting lines where fins and gates are removed by die trimming.
5.3 Cast surfaces are frequently contaminated with par
...