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Materials Science Perspective on Substance Restriction Legislation . Timothy McGrady Chairman, ASTM International Committee F40 on Declarable Substances in Materials Principal Scientist, IMR Test Labs. Materials Science.

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materials science perspective on substance restriction legislation

Materials Science Perspective on Substance Restriction Legislation

Timothy McGrady

Chairman, ASTM International Committee F40 on Declarable Substances in Materials

Principal Scientist, IMR Test Labs

materials science
Materials Science
  • Materials Science is the study of the characteristics, behavior and properties of all types of materials
  • Includes: chemical composition, mechanical properties, metallography, corrosion and environmental effects, failure analysis, weld inspection
  • Materials testing may be conducted on raw materials, processed materials, materials in use or materials within finished goods
materials science3
Materials Science
  • Mature science – for example, ASTM International has been developing standards for testing and specifying materials for over 100 years
  • ASTM has approximately 140 committees; each committee has jurisdiction over certain types of materials or specific uses of materials
    • For example, Committee E01 focuses on test methods for metals and ores; Committee B09 focuses on powdered metallurgy
  • ASTM Committees are made up of producers, inspectors and users of materials
materials science versus environmental testing
Materials Science versus Environmental Testing
  • Some common methodology, but otherwise very different analytical sectors
  • Environmental test methods designed for analysis of air, soil, water and sludge
  • Material test methods designed for specific types of materials; for example, there are separate methods for analysis of aluminum, steel, copper, and nickel alloys; there are further differences in methods within base metal groups (analysis of stainless steel different than analysis of carbon steel)
materials science versus environmental testing5
Materials Science versus Environmental Testing
  • In the United States, soil, air and water samples are sent to environmental laboratories who are accredited to perform EPA tests.
  • Metals, plastics, composites and other materials are sent to independent materials analysis laboratories who are accredited to perform various physical, chemical and structural tests. Test methods used are typically ASTM standards
  • Materials laboratories typically do not analyze environmental samples; likewise, environmental laboratories typically do not analyze materials
materials science versus environmental testing6
Materials Science versus Environmental Testing
  • Inappropriate to apply test methods for analysis of soil, air and water to analysis of metals, plastics and composites; the reverse is also true
  • Having materials analyzed by EPA methods is analogous to sending a suit to the hairdresser to have it cleaned: the results will be unsatisfactory.
  • Unfortunately, it has not been clear whether RoHS requires environmental or materials testing
  • Since products are made of materials, RoHS requires materials testing!
  • Easy to test: send known samples to both types of labs (“blind” round-robin tests)
risk assessment
Risk Assessment
  • What is the risk of hazardous substances being present in a particular material?
  • How do we know whether hazardous substances are present?
  • Two ways to know: 1) empirical knowledge and 2) knowledge based on logic and scientific principles
  • Empirical Knowledge = a posteriori knowledge; based on measurement
  • Logic/Scientific Principles = a priori knowledge; based on deduction and knowledge
hexavalent chromium measurements big problem in metal industries
Hexavalent Chromium measurements = big problem in metal industries
  • EU says Cr6+ must be measured in weight percent within chromate conversion coating.
  • Industry standard is mass/area, units = µg/cm2
  • Cannot measure total mass of coating; it is too thin and is part of substrate
  • Chromate conversion coating thicknesses are 10 – 1000 nanometers!
  • Cannot “mechanically disjoint” such a coating from metal – think about a machine screw
  • Industry must have proper guidance!
homogeneous material
Homogeneous material
  • European Commission did not give legal definition of “homogeneous material”
  • Industry needs definition
  • Some will grind up complex assemblies prior to testing – poor analytical technique
  • Some will test only each material if possible
  • Testing materials instead of semi-finished and finished products would save industry confusion and high cost
eu rohs why grinding parts is poor analytical technique
EU RoHS: Why grinding parts is poor analytical technique
  • Consider chip capacitor on previous slide
  • PbO is exempt in ceramic portion of chip capacitor
  • Pb in solder is not exempt
  • If you grind up chip, you mix exempt and non-exempt Pb
  • Test yields total Pb
  • Based on result, does product conform?
  • Cannot say product conforms or is non-conforming
rohs materials declarations
RoHS Materials Declarations
  • RoHS Material Declarations are lists of substances compiled from laws and customer requirements
  • Often give substance name and maximum concentrations allowed
  • Do not give test methods
  • Do not advise on which substances to test in which case
  • May become legal documents meant to solely to transfer liability to suppliers
  • Many different Materials Declaration documents
materials declarations
Materials Declarations
  • Can suppliers fill out documents without proper test methods in place?
  • Documents are legal instruments – must be able to provide good information
  • Supply chain is getting poor results from laboratories (EPA methods)
  • XRF so far only good for screening (gross deviations from RoHS limits)
  • ASTM: information should be gathered on materials, not parts or finished goods
supply chain model analysis
Supply Chain Model - Analysis

Easiest to test, routinely tested

Raw Materials

Fewest number of companies

Manufactured Materials

Fewest number of items to test

Parts/Components

Greatest number of companies

Greatest number of items to test: number in billions

Sub-assemblies

As complexity increases, number of items to test and testing difficulty increases, as does cost

Finished Products

how standards are used
How Standards Are Used

Material specifications (standards) are quite often referenced in purchase orders.

This greatly simplifies ordering, particularly where requirements are complex.

Both parties (buyer and seller) have access to the standard.

Material Standard

Contract (Purchase Order)

Buyer

Seller

how standards are used17
How Standards Are Used

A standard test method is used to check whether the technical requirements of the material specification have been, or will be, met. Both parties have access to the standard test method.

Test Method

Material Standard

Contract (Purchase Order)

Buyer

Seller

standards and conformity assessment model
Standards and Conformity Assessment Model

SI Units

Certified Reference Material

Test Method

Material Standard

Contract (Purchase Order)

Buyer

Seller

standards and conformity assessment model19
Standards and Conformity Assessment Model
  • The model as described allows check and balance between parties
  • The model allows purchase orders to be assessed as legal contracts
    • Requirements are clear
    • Assessment of conformance is possible
    • Proof of nonconformance can lead to remedy
    • Supporting conformance data is legally defensible, if test is done correctly.
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