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July 2012 4Word Editorial

Posted in Features on July 1, 2012
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Tom Kingston from Spidertrax Off-Road is an engineer. He recently blogged about the results an independent testing lab found when testing domestic and imported wheel spacers. This is important information, so with Tom's permission, I want to share his blog with you below:

The seemingly unending debate of outsourcing and offshoring is back on top of America's "What Matters Most" list. [Because I'm] the proud co-owner of Spidertrax Off-Road, an American company that designs and manufactures its products in-house, it should come [as] no surprise what side of this debate I sit. My interests however in publishing this article lie not in politics but in engineering ethics, focusing not on "you get what you pay for" but rather "you didn't get what was advertised."

Below is a detailed mechanical and material analysis between a Spidertrax JK Wheel Spacer (domestic) and an "Unnamed Brand"* JK Wheel Spacer (import). The takeaway here is not so much one product being superior to another. The issue is with the import wheel spacer being advertised as using 6061-T6 aluminum, the same high-quality material used in our domestic wheel spacer. Although these claims leave the impression that both products are virtually identical, the analysis detailed below tells another story.

*Before moving onto the results, I wanted to clear up any confusion ahead of time regarding the use of "Unnamed Brand". The conflict in sharing this identity comes from singling out just one manufacturer as we have duplicated these same test results from other import wheel spacer manufacturers. Therefore, in an effort in "taking the high road" the import manufacturer in this test will remain nameless and be referred to only as "Unnamed Brand."

Tensile Test (Aluminum Spacer)
Both domestic and import JK wheel spacers are advertised as using 6061-T6 aluminum. As referenced on MatWeb, 6061-T6 should provide a minimum tensile strength (yield) of 40,000 psi and a minimum tensile strength (ultimate) of 45,000 psi.

SpiderTrax JK Wheel Spacer (Domestic)
  Yield Strength Tensile Strength Elongation Fracture
Identity Diameter In Area In Load (lb) lb/in Load (lb> lb/in in/in % Location
1 0.1600 0.0201 880 43,800 960 47,800 0.70 9 g
"Unnamed Brand" JK Wheel Spacer (Import)
  Yield Strength Tensile Strength Elongation Fracture
Identity Diameter In Area In Load (lb) lb/in Load (lb> lb/in in/in % Location
A1 0.2520 0.0499 1,555 31,200 1,566 31,400 1.03 3 g

As shown above, our domestic wheel spacer exceeds the minimum requirements for 6061-T6 (as advertised). The import wheel spacer, on the other hand, is off almost 35 percent in terms of tensile strength for 6061-T6 (not as advertised). What is just as, if not more, concerning is the closeness in value between yield strength and tensile strength for the import spacer. This closeness in value suggests the material is cast and not billet (not as advertised).

Chemical Analysis (Aluminum Spacer)
This test confirms that, although there are differences in material composition as shown below, both our domestic wheel spacer and import wheel spacer conform to a 6061 series grade.

There is an important distinction made when combining the results of both the tensile test and chemical analysis, though. When combined, the results clearly show our domestic wheel spacer is indeed billet 6061-T6 (as advertised) while the import wheel spacer is cast 6061 (not as advertised).

SpiderTrax JK
Wheel Spacer
"Unnamed Brand
JK Wheel Spacer
Silicon .66 | Silicon .41
Iron .20 | Iron .14
Copper .28 | Copper .18
Manganese .05 | Manganese <.01
Magnesium 1.02 | Magnesium .93
Chromium .09 | Chromium .04
Nickel .02 | Nickel .01
Zinc .09 | Zinc .01
Titanium .03 | Titanium .01
Lead .04 | Lead <.01
Tin <.01 | Tin <.01
Beryllium .02 | Beryllium .02
Aluminum Base | Aluminum Base
Other Elements .04 | Other Elements .02
Other Totals <.09 | Other Totals <.05

Hardness (Wheel Stud)
The last test is a cross-sectional hardness traverse on the wheel stud (a component that is pressed into the wheel spacer).

JK Wheel Spacer
"Unnamed Brand"
Jk Wheel Spacer
  HK500 HRC .002 157 77 HRB
.002 390.4 39.0 .004 167 81 HRB
.004 390.4 39.0 .006 221 94 HRB
.006 402.4 40.0 .008 269 23.5 HRC
.008 402.4 40.0 .010 278 25 HRC
.010 408.4 40.5 .015 278 25 HRC
Core 379.0 38.0 Core 292 27.5 HRC

The results, as per SAE J429, indicate our domestic wheel stud exceeds Grade 8 specification (as advertised) while the import wheel stud meets Grade 5 specification (not as advertised).

As shown in the above analysis, our domestic wheel spacers are manufactured from billet 6061-T6 aluminum and run Grade 8 wheel studs as advertised. Although the import wheel spacer is advertised using these same high-quality materials, the above analysis proves it is manufactured out of nothing more than cast 6061 running Grade 5 wheel studs. "Buyer Beware" certainly doesn't capture these outrageous findings.

All testing as detailed in this article was performed by Colorado Metallurgical Services (CMS). Spidertrax Inc. (Spidertrax Off-Road) is not affiliated with or a subsidiary of CMS.

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