Supply Chain · Source
Dual Sourcing
Qualify a second source for anything that stops production, and split volumes to keep both suppliers honest.
- Time40 min
- FormatSmall group
- StageSource
Dual Sourcing: what it is and why it works
Dual sourcing means qualifying and actively using a second supplier for an input whose loss would stop production. The card starts with components that are single sourced and have real switching cost, ranks them by how quickly and severely a supply failure would stop your operation, and qualifies an alternative for the top items even if it costs more. Volume is then split between the two sources, often with a larger share to the primary, so both remain active, familiar with your requirements and comparable on price, quality and delivery. The premium paid for resilience is reviewed regularly against the risk it covers.
Dual sourcing works because a backup supplier is only useful if it can deliver when needed. A source that has been qualified on paper but never received orders usually needs weeks or months to ramp up, relearn specifications and secure its own materials. Regular volume keeps tooling, processes and relationships ready and gives a continuous benchmark that discourages complacency. It is not free: split volume can raise unit prices, double qualification and tooling costs, and add management effort, which is why the card limits it to high-impact items. It follows from the supplier risk scorecard and the Kraljic matrix, and complements backup plans for items where a second source is not feasible.
What you need
- A list of single-sourced components, with annual volume and switching or qualification cost
- Stop-production impact for each: how fast the line would stop and at what cost per day
- Candidate alternative suppliers and their technical capability
- Qualification requirements from engineering, quality and any customer approval rules
What you get
- A ranked list of single-source items by stop-production impact
- A qualification plan and timeline for the top items
- A volume split rule for each dual-sourced item
- A quarterly review of the premium paid versus the risk covered
When to use it
When single sourcing was chosen for price and kept for inertia.
How to do it, step by step
- Identify components with single sources and real switching cost.
- Rank them by stop-production impact.
- For the top items, qualify a second source even at a price premium.
- Split volumes to keep both sources warm and comparable.
- Review the premium quarterly — resilience has a price, and a ceiling.
Worked example: Second source for a membrane housing
Illustrative scenario — figures are realistic but not from a real company.
A builder of containerized water treatment units bought fiberglass membrane pressure vessels from a single supplier. The vessels represented about $1.1 million a year, and each unit could not ship without them. A three-week quality hold at the supplier the previous year had delayed four customer projects.
- The engineering and purchasing team listed eleven single-source components and ranked them by days to stop shipment and cost of delay. The pressure vessels ranked first, followed by a control panel enclosure.
- They identified two alternative manufacturers with suitable pressure ratings and certifications, and ran document review, a factory visit and a trial order of 20 vessels with hydrostatic testing at receipt.
- One candidate passed. Its price was about 7% higher than the incumbent, partly due to lower volume.
- The team set a 70/30 split, with both suppliers receiving monthly releases, and added a clause allowing the share to shift to up to 50/50 during disruptions.
Result. The resilience premium came to roughly $23,000 a year, and competition led the incumbent to shorten its lead time from ten to seven weeks. When the incumbent had a resin shortage the following year, the second source absorbed most of the volume for two months and no project slipped. The team treated the premium as an insurance cost reviewed each quarter.
Common pitfalls and how to avoid them
- Qualifying a second source and then never ordering from it.Give the second source regular volume so it stays ready and its performance is measured.
- Choosing a second supplier that depends on the same raw material source or region.Check sub-tier dependencies and geography so the two sources do not share the same failure point.
- Dual sourcing every item, which raises cost and dilutes volume.Limit dual sourcing to items ranked high on stop-production impact and switching cost.
- Splitting volume evenly by default without considering scale effects.Set a split that keeps both sources active while preserving reasonable pricing, and adjust it by performance.
Frequently asked questions
What is the difference between single sourcing and dual sourcing?
Single sourcing buys an item from one supplier, which can simplify management, maximize volume leverage and support close collaboration, but creates dependency. Dual sourcing uses two qualified suppliers for the same item, reducing the chance that one failure stops supply and keeping price and performance comparable, at the cost of some scale and extra management. Sole sourcing refers to cases where only one capable supplier exists.
How should you split volume between two suppliers?
Many companies give the primary supplier the larger share, such as 60 to 80%, and the secondary enough to keep it active and experienced. The right split depends on scale economies, tooling, capacity and relative performance. Some contracts link the split to scorecards so better performance earns more volume, and include provisions for shifting volume during disruptions.
Is dual sourcing worth the extra cost?
It is worth it when the expected cost of a supply failure, meaning the probability multiplied by the cost of lost production, penalties and customer impact, exceeds the premium for maintaining two sources. For items that stop production quickly and take months to requalify, that is often the case. For low-impact or easily substituted items, buffer stock or simple backup plans are usually cheaper.
Origin
Sourcing risk practice — supply chain management literature, 1990s.
Used in these playbooks
Supplier crisis room 90 min
A supplier just failed: map the exposure, pick the alternates, assign actions — in 90 minutes.
Related methods
- Supplier Risk ScorecardScore key suppliers on financial health, geography, capacity, single-point dependency and quality history.
- Backup Supply PlansFor every critical input, document the alternate source, the qualification gap, and the switching trigger…
- Kraljic MatrixSegment suppliers by impact on profit and supply risk: routine, leverage, bottleneck, critical — and manage…
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