Whether you’re at the point of learning to design a simple amplifier circuit, or you’ve moved up to integrating microcontrollers on your board layouts, you face a universal engineering challenge – finding the right parts you need for your design, when you need them.
The truth is, if you’re at the learning stage where you are just cobbling together prototypes to see if they work, you can usually buy, beg, borrow, or re-purpose the parts you need since the number is usually small.
As your career in electronics advances, however, at some point, you’ll need to consider upping your procurement of necessary parts. With that usually comes the question – should I buy extra parts, and how many should I buy? This is known as overage, and determining just the right amount of electronic component overage to buy is a question that nags both new engineers and seasoned purchasing personnel at some of the largest companies.
Over-ordering of electronic components can be a smart strategy, and it is practiced for many reasons, including spoilage in production, loss of small parts, out-of-spec devices, unanticipated part shortages, spare parts inventory, end-of-life (EOL) notices from suppliers, expected price hikes, and others.
Since you’re probably in the learning process while visiting us here at CircuitBread, you may not have to worry about ordering parts in bulk. But since many CircuitBread users go on to careers in technical design or procurement, here are some tips to remember about ordering excess parts to meet your future needs:
- You usually don’t have to worry about parts overages if you’re working on prototypes unless a specific component is custom or hard to find or if your soldering skills are really marginal. If you’re nervous, order one or two extra of any specific part, remembering that you’ll probably be more careful with more expensive parts.
- If you’re concerned about finding a particular part in the future, ask the supplier or an authorized distributor for their take on anticipated availability.
- If you’re doing limited production, 5% overage planning is the general suggestion. This usually allows for production or supply issues.
- You’ll find that you typically lose or ruin small components due to handling issues, particularly when you are producing boards by hand. Tiny passive components, like chip capacitors, can even be a problem for large machine insertion production lines.
- If you’ve advanced to a slightly larger run of your product but still produced in-house, a safe parts overage assumption is 5-10% to allow for hand-produced damage, errors, or partial loss.
- Advanced manufacturing at the mass production level usually means having your boards built and populated by a contract manufacturer. This means machine-inserted components on reels, with excess ordering limited to full reels of parts. In this case, overages can run from 10-20%.
Some Tools to Help
As in many other situations, it is often best to understand and take advantage of available tools to make your work life easier. One of the best ones to learn and remember to always use is a simple Bill of Materials (BOM). A BOM is a complete list of all the components and materials that you need for the assembly of your product, along with part numbers, quantities, prices, or other specs that may be useful to you. It can help keep you organized, control costs, and manage waste. CircuitBread Friend and industry distributor OnlineComponents.com offers a sample BOM you can try out at: www.onlinecomponents.com/en/bomquotes.
There are also numerous software packages of increasing complexity and usefulness that you may want to begin learning about. As you move forward, you may find yourself using Materials Requirements Planning (MRP) packages like MPR Easy and Total ETO for inventory management. While not necessary if you are just beginning to learn electronics, it’s good to know they are out there.
Summary
OnlineComponents.com and Master Electronics are both experts in this area, and they have an even more in-depth overview that may be beneficial if you still have more questions about this topic. In the meantime, let’s recap with a quick list of steps to remember about sourcing parts for your designs.
- Always create and use a BOM
- Keep track of what you’ve bought and what you’ve used
- Buy with the future in mind
- Use software tools to help
- Build and rely on connections with suppliers and distributors
Even if you are just starting in electronics, it’s good to learn about parts overage ordering and planning for supply contingencies. A little thought and planning ahead of time can save you needless procurement frustration in the future.
