Customer case · US battery-pack manufacturing
Custom M6 × 272 mm Long Screws for Battery Pack Assembly
We helped a US battery-pack manufacturer take an evolving fastener design through drawing review, sample validation and production delivery.
Project initiated in 2019 · Manufactured by Shi Shi Tong
- Final screw length
- 272 mm
- Thread specification
- M6 × 1.0
- Property class
- 8.8
- Threaded length
- 16 mm
The project
A battery-pack design still in development
The customer develops and manufactures custom battery packs and energy-storage systems. Its initial inquiry, received on January 21, 2019, called for an M6 × 256 mm extra-long socket head screw for a Core Pack assembly.
Over roughly six months of design development, our team worked with the customer's purchasing and engineering teams as length, thread details and surface requirements changed. The final production basis for this part was the customer-approved M6 × 272 mm drawing.
The design needed an extended shank, class 8.8 strength and compatibility with the existing assembly space. That made material planning, forming details, heat-treatment bending risk and finish selection part of the manufacturing review.
The approved part
Final agreed screw specification
Production followed the final confirmed drawing revision, including the change from 273 mm to 272 mm on the later design.
| Product | Extra-long socket head machine screw |
|---|---|
| Thread / pitch | M6 / 1.0 mm |
| Specified length | 272 mm |
| Threaded length | 16 mm |
| Shank diameter | 6 mm |
| Head diameter / height | 10 mm / 6 mm |
| Drive / minimum recess depth | Hex socket / 3 mm minimum |
| Material / property class | Carbon steel / 8.8 |
| Construction | Head and shank formed as one piece |
| Surface finish | Black oxide |
| End feature / forming line | Chamfered end / forming line accepted |
A forming detail agreed before production
We explained that a fine line can remain below the head after forming. The customer accepted that appearance, so additional removal work was not required.
Our engineering response
Three decisions that shaped the order
Plan the material around sample validation
The target material carried a substantial minimum purchase quantity. We offered a geometry-and-fit sample route using alternative stock, or samples made from the target material with the remaining stock reserved for production. The customer placed a production order with sample performance confirmation before the production run.
Review forming and thread-end details
We proposed a one-piece head-and-shank route rather than a welded extension. During drawing review, we also presented a manufacturable thread-end alternative for the customer's assessment, with assembly function and manufacturing cost considered together. Any change required customer confirmation.
Resolve insulation and assembly-space requirements
The customer initially requested 1000V electrical insulation. A sleeve would have increased the outside diameter and forced changes to mating parts, so the sleeve approach was not accepted. The customer later removed the insulation requirement from our screw supply scope. We recommended black oxide instead of bare carbon steel to address corrosion-protection needs during shipment.
From inquiry to shipment
Keep production aligned with the confirmed design
- January 2019
Initial drawing review
Review the M6 × 256 mm inquiry, strength requirement, material plan and heat-treatment bending risk.
- Design development
Coordinate changing requirements
Discuss parallel assembly designs, forming appearance, thread details and insulation options.
- Final drawing
Freeze the 272 mm length
Use the customer's final revision as the order and production basis, together with the agreed finish.
- Sample approval
Verify the assembly
Submit samples for performance confirmation and the customer's actual assembly validation.
- Production & delivery
Ship the approved part
Manufacture to the confirmed design and arrange the customer's requested staged shipments.
The result
Sample-approved screws moved into production
The samples passed the customer's actual assembly validation. We then completed production and delivery against the agreed strength, appearance, corrosion-protection and shipment requirements.
- Assembly fit confirmed through the customer's sample validation.
- Final requirements carried into production for the M6 × 272 mm part.
- Staged delivery supported with sample packaging and wooden-crate packing for bulk shipment.
Discuss your application
Need a long screw built around your assembly?
Send your drawing and the requirements that control fit and performance. Our team can review the manufacturing route, sample plan and production requirements for your part.
- Thread, length, head and drive geometry
- Material grade, strength and surface finish
- Critical tolerances and mating-part details
- Sample quantity, production demand and target delivery
Prefer email? info@fastenbydesign.com
Have an electrical-insulation requirement? Include it with the drawing so the treatment and assembly space can be reviewed together.
