INDUSTRIAL INFO-TAINMENT Wiring Harness News SEPTEMBER / OCTOBER 2022 25
Processing Electric Vehicle Heavy Cables
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TTI + 3M
Figure 3 . Lateral Processing of HLC Wires .
Flexibility is the Word with 3M ™ Round Conductor Flat , Controlled Impedance Cable , 7700 Series .
Figure 4 . Clockwise from top left , peripheral bayonet and tangent slicers .
Manufacturing challenges .
By far one of the major challenges that EV wire manufacturers face is the exposure and / or removal of each single layer . Each layer presents differences in material and thickness ; thus , the tool used to expose or remove these layers has to have the design capability of doing so . The tools currently being used are rotary slicing blades . Although there are many distinct OEM designs , we can classify them into three major types shown in Figure 4 :
• Bayonet .
• Tangent .
• Peripheral .
Periphery slice cut and slug removal .
Slice cut . Bayonet and tangent slicing blades are designs used for rotary processing systems that allow penetration adjustability by programmable adjusting parameters on the equipment ’ s processing module . This achieves precise cuts on each one of the layers . On the other hand , the round geometry of peripheral slicing blades is sized for a specific layer , based on the layer ’ s cut perimeter . So , for each layer to remove or expose , you would need individually sized peripheral slicing blades .
Layer removal .
Once you have cut into each layer , the next challenge is to remove the resulting slug . In order to do this , you either use the pushing method or the pulling method . The vast majority of the current stripping modules use the pushing method to do this . Which method to use strongly depends on the material ’ s property as well as the dimensionality of the material Itself . Materials such as films are exceedingly difficult to remove since they are extremely thin and neither a push nor pull approach works 100 % of the time . Woven materials such as shields are also difficult to remove because of their loose construction and thinness . Shield layers are normally folded back to expose the subjacent insulation layer .
Insulation slug removal .
Heavy layered cables for the EV powertrains require sufficient flexibility for efficient installation in the available space in the vehicle . Flexible insulation material has “ rubbery ” qualities . This translates into elasticity and compressibility characteristics . The combination of the elastic attributes of the insulation with the conductor core structure complicates the slug removal operation because
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