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Specific examples and key points for selecting screws to achieve cost reduction
Introduction
Due to rising raw material and labor costs and the increasing complexity of supply chains, “high component costs” and “increased man-hours” have become chronic challenges in the manufacturing industry. Among these, fastening components such as screws and bolts, while accounting for a small portion of the product cost at an average of around 5%, are crucial parts that influence up to 50% of assembly man-hours. Proper screw selection is a “double-punch” cost reduction measure that affects both material costs and labor man-hours.
Based on the experience Ohta Vietnam has cultivated on-site in various Asian countries, this article will quantitatively show the impact of screw selection on costs, while introducing practical improvement measures from four perspectives: manufacturing method, standards, quantity, and assembly man-hours. Rather than just theory, the aim is to provide guidelines that readers can immediately utilize in their own company projects by focusing on case studies that have proven effective at bases in Asia, including Vietnam.
The intended readers are design and purchasing managers in Japan, and production technology and procurement managers at local factories in Vietnam. It is our hope that those who are struggling with “which screw to choose” for cross-border procurement or mass production ramp-ups can achieve sustainable screw cost reduction with this article as a guide.
Source: Western Fastener
Overall Picture of Screw Costs｜Cost Breakdown and 4 Perspectives
Breakdown of Screw Costs｜Material, Processing, Surface Treatment, Logistics
The total cost of a screw is composed of the four elements in the table below.
| Cost Element | Representative Content | Estimated Composition Ratio* |
| Material Cost | Base materials such as carbon steel, stainless steel, titanium + wire processing costs | 35–50% |
| Processing Cost | Cold heading, cutting, thread rolling, heat treatment | 25–40% |
| Surface Treatment Cost | Zinc plating, nickel plating, black oxide coating, lubricant application | 10–15% |
| Logistics Cost | Packaging, packing, transportation, inventory and lot management | 5–10% |
*Ohta Vietnam internal average values (vary depending on product specifications and lot size).
Even for special machined parts where processing costs tend to be high, it is possible to achieve a reduction of up to 70% by switching to cold heading or thread rolling.
Source: Ikeda Kinzoku Kogyo Co., Ltd.
4 Perspectives for Cost Reduction｜Manufacturing Method, Standard Selection, Quantity Optimization, Assembly Man-hours
- Optimization of Manufacturing Method – Switch to low-man-hour processes such as cutting → cold heading, lathe → thread rolling, to reduce processing costs and lead times.
- Promotion of Standards/Standardization – Replace custom screws with JIS/ISO standard screws to compress mold and procurement costs.
- Review of Quantity and Lot Design – Suppress unit prices and logistics costs with 4–6 month lots that consolidate annual demand.
- Reduction of Assembly Man-hours – Shorten line tact time by reducing the number of screws or introducing rivets and integrated fasteners.
Source: Marumono/Lathe Machining.COM / MONOist
Benefits and Risks of Procurement in Vietnam
Benefits
- Labor costs are approximately 1/3 of Japan’s, compressing component unit prices by an average of 15–25%.
- There are Japanese and local fastener clusters from Haiphong to Ho Chi Minh City, capable of handling high-mix, low-volume production.
- Tariff reduction through utilization of EPAs (e.g., EVFTA), and shorter delivery times for logistics within the ASEAN region.
Risks and Countermeasures
- Variation in Quality Standards → Guarantee quality by specifying ISO9001/IATF16949 certified suppliers and using sampling inspection + image sorting machines.
- Lead Time Extension → Cover with hybrid transportation of regular shipping + air freight, and domestic stock for emergency lots.
- Communication Gaps → Prevent specification discrepancies with resident Japanese engineers & Japanese drawings/process FMEA.
Procurement in Vietnam is an effective measure to lower both processing and logistics costs simultaneously, but quality governance determines its success or failure. At Ohta Vietnam, we have made on-site audits and Japanese reports a standard service to minimize risks.
Source: Ohta Vietnam internal survey (2025)
Learning Screw Cost Reduction with Specific Examples
Screw Cost Reduction by Optimizing Manufacturing Method
By switching a low-head hex socket bolt (M2), which was previously assumed to be machined, to a process centered on cold heading, the purchase unit price was reduced by approximately 70%, and the lead time was also stabilized. Cold heading requires a mold investment, but it can be amortized in a short period by producing 4–6 months’ worth at once. Furthermore, changing from lathe to thread rolling reduced chip costs and swarf disposal fees, and quality was also improved by uniforming the surface roughness.
Source: Ikeda Kinzoku Kogyo Co., Ltd. / Marumono/Lathe Machining.COM
Screw Cost Reduction by Reducing Assembly Man-hours
In a case where 40 screws used to fix 20 sheet metal stays on an AV equipment chassis were replaced with 20 rivets, tool changes were halved, and the assembly tact time per unit was shortened by approximately 25%. For locations where riveting is difficult, additional effects are obtained by adopting SEMS screws with integrated washers or pre-coated bolts, thereby simplifying manual work processes.
Source: MONOist
Screw Cost Reduction by Optimizing Standards
In a project where a special screw for equipment was replaced with a standard JIS hex socket bolt, the lot unit price was reduced by 30%, and the procurement lead time was shortened to less than half. By standardizing the head shape, bit changes on the line side also became unnecessary, reducing setup change time by 10 hours per month.
Source: Tomita Rashi Co., Ltd.
Cost Optimization through Quantity and Lot Design
By switching an M2 low-head bolt, which had been repeatedly ordered monthly, to lot production for 4–6 months’ worth, the unit price was further reduced by 15%, and the risk of stockouts was also significantly decreased. By combining planned ordering with safety stock, it is possible to respond flexibly to demand fluctuations.
Source: Ikeda Kinzoku Kogyo Co., Ltd. (Implementation Effect Report)
Summary｜Sustainable Cost Reduction through Screw Selection
By progressively optimizing screw selection from the four perspectives of manufacturing method, assembly man-hours, standards, and quantity, it is possible to simultaneously achieve up to a 70% reduction in processing costs, a 25% shortening of line tact time, and a 30% reduction in unit price and logistics costs. By combining the switch to cold heading/thread rolling, reduction of screw quantity, JIS/ISO standardization, and 4–6 month lot ordering, long-term and stable cost reduction is possible, leveraging the cost advantages of procurement in Vietnam and the quality audits of Ohta Vietnam. We encourage all readers to try implementing the points from this article at their own sites.
Conclusion
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