Exhibit 3 Test Method for Tungsten Carbide Inserts in Underbody Blades.docx

This is a test method exhibit for Michigan Department of Transportation (MDOT) specifications regarding tungsten carbide inserts in replaceable cutting edges for snowplow underbody blades. The document, Michigan Test Method 719-01, establishes the procedures and requirements for testing the brazed connection between tungsten carbide inserts and underbody blade base materials to ensure compliance with current MDOT specifications. Contractors must provide documentation that their blades meet these specifications, or MDOT will conduct verification testing. Testing samples consist of two blades per shipment (defined as any delivery within a three-week period) or four blades per yearly order, whichever is greater, with four sample specimens extracted from each blade—two samples from each third point. The testing equipment required includes an electro-hydraulic test machine with a fixture for shear testing and a microscope with a minimum 20X magnification.

The brazing material must be a high-strength alloy type with a minimum rated shear strength of 207,000 kPa (30,000 psi), supported by manufacturer certification submitted with invoices to the MDOT Central Office. Test specimens are machined to specific dimensions (19-22 mm thickness by 19 mm by 25 mm length), and shear loads are applied along the longitudinal axis at a rate not exceeding 350 lbft/sec. Acceptance of the entire shipment requires that the averaged shear strength of each tested blade meets or exceeds the minimum requirement of 138,000 kPa (20,000 psi). If one originally sampled blade fails this requirement, a second blade from the same shipment must be tested; failure of this second blade results in rejection of the entire shipment. Additionally, visual inspection requirements mandate secure brazing over the entire length and surface of the blade groove with no evidence of voids, brazing gaps, excessive voids, or oxidized surfaces that prevent brazing material adhesion.