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Frequently Asked Questions
May 2005
Quick scroll to questions relating to:
Aluminum
Cadmium
Chromium
Lead
Plastic
Stainless Steel
Zinc Plating
Q.
- What are the RoHS concerns related to aluminum products?
A.
- The
issue with aluminum and RoHS is that some aluminum alloys, such as 2011,
contain lead in amounts which could exceed the 0.4% allowed by the exception
in clause 6 of the Annex of the RoHS directive. Fortunately, the alloys
we use for standard parts do not contain any intentional additions of
lead and therefore have always been RoHS compliant.
With
regards to chromium, any chromium present in aluminum will be in the
metallic or zero valence state and is therefore not an RoHS concern
since the RoHS directive restricts only hexavalent chromium which only
exists in certain compounds in which the chromium has a valence state
of +6 (hexavalent). A chromate finish applied to aluminum could contain
hexavalent compounds. We do not apply any type of chromate finish to
any of our standard aluminum products.
Q.
- Does the RoHS Directive ban the use of cadmium plating on fasteners?
A.
- Clause 8 of the Annex of the RoHS directive grants an exception allowing
cadmium plating to be used unless it is banned under Directive 91/338/EEC.
Directive 91/338/EEC amends an earlier directive 76/769/EEC. The amended
text bans cadmium from certain applications, primarily those involving
contact with food and hardware that could have direct contact to human
skin or contact with indoor air. The amended text clearly allows cadmium
plating in aerospace applications and other safety critical sectors.
Therefore, RoHS compliance of cadmium plating depends on the classification
of the end product and PennEngineering, as a fastener supplier, can
not determine RoHS compliance of cadmium plating.
Q.
- Does the RoHS directive ban all chromium?
A.
- Chromium can exist in four states. Metallic, divalent, trivalent and
hexavalent. In some compounds chromium is in the hexavalent state (valence
of +6) and many of these compounds are hazardous. The current European
RoHS directive bans the use of six substances, one of which is hexavalent
chromium. The ban on hexavalent chromium targets primarily corrosion
resistant coatings, such as the chromate conversion coatings applied
to zinc plating. Metallic chromium found in stainless steel is not a
RoHS substance.
Q.
- What type of chromium is in the conversion coating applied to zinc
plating?
A.
- The substance of concern with regard to chromate conversion coatings
on zinc plating and RoHS compliance is hexavalent chromium. The RoHS
Directive restricts hexavalent chromium, but does not restrict less
hazardous trivalent chromium. Historically, both clear and yellow chromate
conversion coatings contained hexavalent chromium compounds. In recent
years suppliers of chromate conversion coating materials have been working
hard to develop chromate conversion coatings that contain only trivalent
chromium compounds and provide acceptable corrosion resistance. Presently
there are a number of such products available in clear. Yellow chromates
have been more difficult to develop because the corrosion resistance
requirements are greater. For example, ASTM B 633 requires 12 hours
of neutral salt spray to white corrosion for clear chromate, but 96
hours for yellow chromate.
With
regard to our standard zinc plated PEM® brand steel fasteners, we
began using a trivalent clear chromate in June of 2002 for all or product
with finish suffix ZI. Therefore all -ZI product plated after June 2002
is RoHS compliant. Also, we began using trivalent chromate in our optional
zinc and yellow (suffix -ZC) plating on March 1, 2006. Therefore, this
finish is compliant as of that date.
Q.
- What type of chromium is in stainless steel?
A.
- In stainless steel, chromium is in the metallic state, which is not
hazardous.
Q.
- What type of chromium is in the oxide layer created by passivating
stainless steel?
A.
- Our research has found this layer to be dichromium trioxide or Cr2O3,
which is a trivalent compound as opposed to chromium trioxide or CrO3,
which is a hexavalent compound.
Q.
- What does the term, "Lead Free" mean?
A.
- The term "Lead Free" can have two meanings. First, it could simply
mean that the product has no lead. Secondly, it could mean that the
material is compatible with a lead free soldering process. In the second
case the process must be specified.
Q.
- What specific lead exceptions relate to fasteners?
A.
- Claus 6 of the RoHS annex states that up to 0.35% can be present as
an alloying element in steel; up to 4.0% as an alloying element in copper;
and up to 0.4% as an alloying element in aluminum. All of our fasteners
are compliant to this annex.
Q.
- Do you use any non-compliant plastics in any of your products?
A.
- No. All of the plastic used in our locking and hybrid products are
RoHS compliant.
