In addition to providing cosmetic advantages, the function of most platings, coatings and finishes is to provide a certain level of corrosion resistance. Customers should be aware that if they order and receive un-plated or uncoated steel fasteners (usually designated with an “X” part number suffix), the parts may not have the necessary corrosion resistance and will rust, corrode, discolor or otherwise degrade at a much more accelerated rate than finished products. While we can investigate, in most cases PennEngineering cannot be responsible for quality issues that may arise from these circumstances.

Black Nitride

Black Nitride and dry to touch oil (BN)

  • Applicable to steel and stainless steel only.
  • Parts are heat treated to give them a thin, hard, durable case with a dark brown to black color.
  • Compound layer meets requirements of Section 3.4 of SAE AMS2753.
  • Dry to touch oil added to improve appearance and corrosion resistance.
  • Parts will withstand 12 hour humidity test (90% to 95% relative humidity at approximately 104°F) with no red rust.

Cadmium Platings

Cadmium Plus Clear Chromate (CI)

Applicable Industry Spec: ASTM B766, CLASS 5, TYPE III
QQ-P 416 Class 3 Type I & clear Chromate

  • The parts shall be capable of passing a 12 hour salt spray test to white corrosion and a minimum of a 100 hour salt spray test to red rust per ASTM B117.
  • Typically, cadmium plus clear chromate offered by PEM is .0002″ minimum of cadmium applied to all significant surfaces. Significant surfaces exclude such features as threads, holes, deep recesses and bases of angles.
  • A clear chromate conversion coating is applied after cadmium plating.
  • Steel parts requiring embrittlement relief after plating are baked according to industry standards.

Cadmium Plus Metric Blue Chromate (CB)

Applicable Industry Spec: ASTM B766, CLASS 5, TYPE II
QQ-P 416 Class 3 & clear dyed blue Chromate

  • The parts shall be capable of passing a 12 hour salt spray test to white corrosion and a minimum of a 100 hour salt spray test to red rust per ASTM B117.
  • Typically, cadmium plus metric blue chromate offered by PEM is .0002″ minimum of cadmium applied to all significant surfaces. Significant surfaces exclude such features as threads, holes, deep recesses and bases of angles.
  • A clear chromate conversion coating with blue dye is applied after cadmium plating.
  • Steel parts requiring embrittlement relief after plating are baked according to industry standards.

Cadmium Plus Olive Drab Chromate (CO)

Applicable Industry Spec: ASTM B766, CLASS 5, TYPE II
QQ-P 416 Class 3, Type II

  • The parts shall be capable of passing a 150 hour salt spray test to white corrosion and a 200 hour salt spray test to red rust per ASTM B117.
  • Typically, cadmium plus olive drab chromate offered by PEM is .0002″ minimum of cadmium applied to all significant surfaces. Significant surfaces exclude such features as threads, holes, deep recesses and bases of angles.
  • An olive drab chromate conversion coating is applied after cadmium plating.
  • Steel parts requiring embrittlement relief after plating are baked according to industry standards.

Cadmium Plus Yellow Chromate (C)

Applicable Industry Spec: ASTM B766, CLASS 5, TYPE II
QQ-P 416 Class 3, Type II

  • The parts shall be capable of passing a 96 hour salt spray test to white corrosion and a minimum of a 200 hour salt spray test to red rust per ASTM B117.
  • Typically, cadmium plus yellow chromate offered by PEM is .0002″ to minimum of cadmium applied to all significant surfaces. Significant surfaces exclude such features as threads, holes, deep recesses and bases of angles.
  • A yellow chromate conversion coating is applied after cadmium plating.
  • Steel parts requiring embrittlement relief after plating are baked according to industry standards.

Cadmium Without Finish Coat (D)

Applicable Industry Spec: ASTM B766, CLASS 5, TYPE I

  • The parts shall be capable of passing a 100 hour salt spray test to red rust per ASTM B117.
  • Typically, cadmium without a finish coat offered by PEM is .0002″ to minimum of cadmium applied to all significant surfaces. Significant surfaces exclude such features as threads, holes, deep recesses and bases of angles.
  • Steel parts requiring embrittlement relief after plating are baked according to industry standards.

Dry Film Lubricants

Carbowax™ (CW)

  • Carbowax™ is a product of the Dow Chemical Company.
  • CARBOWAX™ SENTRY™ PEGs are water soluble linear polymers formed by the addition reaction of ethylene oxide to an ethylene glycol equivalent.
  • The CW finish is applied to product and after drying provides a thin layer of ethylene glycol which provides the part surface with needed lubricity for locking torque performance.
  • There are no industry standards for defining this process.

Electro-Film (EF)

Applicable Industry Spec: MIL-PRF-46010

  • The parts shall be capable of passing an adhesion test, a resistance to fluids test, an endurance life test, and a load carrying capacity test as specified in MIL-PRF-46010.
  • Typically, electofilm coating offered by PEM is .0002″ to .0004″ of M-6002, applied to all surfaces.
  • Parts shall be plated, if required, prior to this operation. Stainless steel parts require an undercoat for proper adherence of this process.
  • Typically applied over .0002 – .0004 Cadmium coat. Can be applied over tin or silver, but the Lubricity is not as good as with Cad.

Molybdenum Disulfide Dry Film Lubricant (MD)

  • Dry film lubricant containing molybdenum disulfide and other lubricating ingredients does not contain graphite or other highly electrically conductive materials. It contains a solvent-based phenolic resin system to bind the ingredients to the fastener surface.
  • The color is a uniform gray/black.
  • The adhesion of this dry film lubricant meets the requirements of ASTM D-2510, Method B.
  • The thermal stability meets the requirements of ASTM D-2511.
  • It is able to resist 24 hours of salt spray per ASTM B-117 with no significant stains on steel with zinc phosphate under plate.
  • It is able to resist 100 hours of salt spray per ASTM B-117 with no significant stains on stainless steel.
  • Dry film lubricant containing molybdenum disulfide and other lubricating ingredients is resistant to the following fluids when tested per ASTM D-2510, Method C:
    1, 1, 1 – Trichloroethane
    JP-4 Jet Fuel, MIL-T-5624
    Synthetic Hydraulic Fluid, MIL-H-83282
    Silicone Damping Fluid, VV-D-1078 Skydrol 500 A
  • The thread lubricating properties facilitate meeting the 15 cycle locking torque reusability requirements of NASM25027 when applied to all metal prevailing torque locknuts.

Solid Film Lubricant (used on M45938/7 and M45938/11 locknuts)

Applicable Industry Spec: SAE AS5272 Type i (Replacement for discontinued MIL-L46010 Type i)

  • Heat cured dry film lubricant suitable for use at temperatures of -90 to 400F.
  • The thread lubricating properties facilitate meeting the 15 cycle locking torque reusability requirements of MIL-DTL-25027 when applied to all metal prevailing torque locknuts.
  • The color is a uniform gray/black
  • This finish system provides salt spray resistance of a minimum of 100 hrs to red rust on significant surfaces when tested per ASTM B117.
  • Does not contain graphite or ozone depleting substances
  • The adhesion of this dry film lubricant meets the requirements of ASTM D-2510, Procedure A.
  • Applied over .0002 – .0004 inch cadmium plating plus yellow chromate per SAE AMS-QQ-P-416, Class 3, Type II.
  • Not RoHS compliant.

Electro-Tin/Solderable Platings

Electro-Tin with Clear Preservative Coating (ET) (DT)

Applicable Industry Spec: ASTM B545, CLASS A and CLASS B

  • When applied to surface mounted (SMT) fasteners, minimum tin thickness on all significant surfaces is .0001 inch meeting ASTM B545, Class A. When applied to all other fastener types minimum tin thickness on all significant surfaces is .0002 inch meeting ASTM B545, Class B. Significant surfaces exclude such features as threads, holes, deep recesses and bases of angles.
  • All tin is electro-deposited from a matte tin bath.
  • When applied to SMT parts the tin is applied over nickel which is applied over copper for optimum solderable shelf life.
  • When applied to base materials with over 5% zinc content copper and nickel barrier layers are used. Although neither layer meets the minimum thickness per ASTM B545, the two layer combination is effective at preventing zinc migration into the tin plating.
  • Parts are stress relief annealed at 300 °F for 1 hour to deter Tin Whisker Growth per iNEMI recommendations.
  • A clear preservative coating is applied after electro-tin plating.
  • Each lot is tested for solderability with lead free solder by the dip and look method.
  • The parts shall be capable of passing an adhesion test per ASTM B545 Appendix X2.2 and ASTM B571, para. 13.2.

Statement of Shelf Life For Solderability

Products finished with electro-plated matte tin (finish designations ET and DT) will experience some loss of solderability over time. The optimal shelf life of any given lot of product varies with the characteristics of the tin plating and the storage environment. With this understanding, the following minimum shelf life times should be used for inventory management:

  • Solderable optimal shelf life of all ET and DT plated PEM products is 36 months from the date of the original packaging.

In order to maximize the solderable shelf life of these products, PennEngineering® recommends the following:

  • Product should remain in original packaging (with desiccant) or equivalent repackaging supplied by an authorized distributor.
  • Storage temperature should be maintained between 5 and 40 °C (41 to 104 °F)
  • Relative humidity should not exceed 80%

Electro-Solder (ES)

Applicable Industry Spec: SAE AMS-P-81728

  • The parts shall be capable of passing an adhesion and solderability test per MIL-P-81728.
  • Typically, electro-solder offered by PEM is .0002″ to minimum of electrodeposited tin-lead plating applied to all significant surfaces. Significant surfaces exclude such features as threads, holes, deep recesses and bases of angles.

Passivation of Stainless Steel

Explanation of typical Passivation Procedures

Passivation is the generic term applied to procedures developed to remove the presence of metallic (free) iron from the surface of stainless steel products. The presence of free iron particles on the surface of stainless steel products can cause the product to show rust spots which should not occur with a clean or “passive” stainless steel surface. A PASSIVE stainless steel surface would have NO free iron particles which could potentially corrode or “rust.”

During the handling and processing operations such as forming, machining and tumbling, particles of iron and tool steel can be embedded or smeared on the surface of the fastener. If allowed to remain, these free iron particles will corrode and show as rust spots.

The passivation process involves submerging the stainless steel fastener into a solution of nitric acid (20-25% by volume), sodium bicarbonate (2-3% by weight) and water or 35% Nitric by volume and water for some period of time. Twenty to thirty minutes is typical. The nitric acid dissolves the embedded or smeared iron and restores the original corrosion-resistant surface to the part.

It is generally considered good practice to passivate parts after many manufacturing processes, however in some applications it may prove unnecessary. When the need for passivation is in doubt, testing can provide the answer. ASTM A380 is a recognized specification which details the specific testing parameters to be met. Parts which pass the “Passivation Test” per ASTM A380 have a surface void of any free iron particles. They are considered passive.

Explanation with regard to PEM Fasteners

Penn Engineering typically lists Passivated and/or Tested per ASTM A380 as it’s passivation procedure. ALL parts are subjected either to a passivation procedure OR are tested for the need for passivation. Those parts which FAIL the passivation test are then passivated. Those passing the test are passive and are not processed further.

For those customers requiring that all parts are passivated and not just tested, a special part number can be assigned and ordered.

Applicable Industry Specifications

  • PASSIVATION per QQ-P-35C, TYPE II or it’s replacement ASTM A967 Nitric I, used as the processing spec. for passivating AISI 303, 410, 416 and 17-4PH stainless steels. Most PEM fasteners manufactured by screw machining methods are passivated to this specification when necessary.
  •  PASSIVATION per QQ-P-35C, TYPE VI or its replacement ASTM A967, Nitric 2, Used as the processing spec. for passivating AISI 302, 304, 305, 316, 900 stainless steel. Most PEM fasteners manufactured by cold-heading or cold-forming methods are passivated to this specification when necessary.
  • PASSIVATION test per ASTM A380 Used for determining if a product needs to be passivated. Detects the presence of free iron on the surface. Those products failing this test are then passivated by one of the above specifications.

Zinc Platings

PennEngineering uses the detection methods defined in the IEC-62321-7-1:2015 to measure hexavalent chrome in the chromate conversion (passivation) layer of our zinc-chromate plated parts to assure they are not hexavalent chromium based as determined by IEC-62321-7-1:2015 and other consensus standards. Concentrations of lead, mercury, poly-brominated Biphenyls (PBB) and polybrominated diphenyl ethers (PBDE), in any as deposited homogenous material must be less than 1000 PPM or 0.1%. The concentration of cadmium must be less than 100 PPM or 0.01%.

Zinc Plus Clear Hexavalent Free Chromate - Part Suffix ZI

Applicable Industry Spec: ASTM B633, SC1, Type III

  • Scope – This includes electrodeposited zinc coatings as applied to steel, copper, brass, and bronze parts to protect them from corrosion. Steel parts requiring embrittlement relief after plating are baked according to industry standards.
  • Plating Thickness – The zinc plating shall be a minimum thickness of .0002 inch (5 µm) on all significant surfaces. Surfaces on which the specified thickness of deposit cannot readily be controlled, such as threads, holes, deep recesses, bases of angles, and similar areas, are exempt from the thickness requirements.
  • Supplementary Finish – Parts shall have a clear hexavalent free chromate conversion coating applied.
  • Testing – The parts shall be capable of passing 12 hour salt spray test per ASTM B117 with no white corrosion products. White corrosion products on external edges or corners shall not be cause for rejection.
    Red corrosion products on surfaces which the specified thickness of deposit cannot readily be controlled, such as threads, holes, deep recesses, bases of angles, and similar areas, shall not be cause for rejection.

Zinc Plus Yellow Hexavalent Free Chromate - Part Suffix ZC

Applicable Industry Spec: ASTM B633, SC1, Type II

  • Scope – This specification covers electrodeposited zinc coatings as applied to steel, copper, brass, and bronze parts to protect them from corrosion. Steel parts requiring embrittlement relief after plating are baked according to industry standards.
  • Plating Thickness – The zinc plating shall be a minimum thickness of .0002 inch (5 µm) on all significant surfaces. Surfaces on which the specified thickness of deposit cannot readily be controlled, such as threads, holes, deep recesses, bases of angles, and similar areas, are exempt from the thickness requirements.
  • Supplementary Finish – Parts shall have an iridescent yellow hex-free chromate conversion coating applied. The parts shall have a yellow/gold color.
  • Testing – The parts shall be capable of passing a salt spray test per ASTM B117. Minimum salt spray requirements are 96 hours with no white corrosion products and 120 hours with no red rust on significant surfaces.
    White corrosion products on external edges or corners shall not be cause for rejection.
    Red corrosion products on surfaces which the specified thickness of deposit cannot readily be controlled, such as threads, holes, deep recesses, bases of angles, and similar areas, shall not be cause for rejection.

Zinc Plus Clear Trivalent Chromate Plus Sealant/Lubricant - Part Suffix LZ

Applicable Industry Spec: ASTM B633, SC1, Type III plus a lubricated topcoat

  • Scope – This specification covers electrodeposited zinc coatings as applied to steel, copper, brass, and bronze parts to protect them from corrosion. Steel parts requiring embrittlement relief after plating are baked according to industry standards and provide lubricity.
  • Plating Thickness – The zinc plating shall be a minimum thickness of .0002 inch (5 µm) on all significant surfaces. Surfaces on which the specified thickness of deposit cannot readily be controlled, such as threads, holes, deep recesses, bases of angles, and similar areas, are exempt from the thickness requirements.
  • Supplementary Finish – Parts shall have a trivalent chromate conversion coating applied and then leached back to a silver – white color with a combination leachant – sealant. The leachant – sealant shall have an integral lubricant.
  • Testing – The parts shall be capable of passing a salt spray test per ASTM B117 or SAE/USCAR-1 after being baked at 120° C for 4 hours. Minimum times are 72 hours with no white corrosion products and 168 hours with no red corrosion products.
    White corrosion products on external edges or corners shall not be cause for rejection.
    Red corrosion products on surfaces which the specified thickness of deposit cannot readily be controlled, such as threads, holes, deep recesses, bases of angles, and similar areas, shall not be cause for rejection.
    The parts shall be capable of passing the appropriate torque / clamping force requirements specified in Ford Spec WZ100 or as required by special customer specifications.

Zinc Plus Other Chromate Conversion Coatings - Part Suffix ZB & BZ

ZB Applicable Industry Spec: ASTM B633, SC1 (5µm), Type III, Black
BZ Applicable Industry Spec: ASTM B633, SC1 (5µm), Type III, Blue

  • Scope Other chromate conversion coatings such as black, blue and olive color are available on special order. These colored chromate coatings offer various degrees of corrosion resistance.

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