What's cheaper & faster for my lab, keep a stock of electronics components or order?

We are four electronic engineers working in a company, and we have a lab, I think we have a logistic issue with our components, this might be a basic study case:

• We have few racks with resistors, capacitors, chips, transistors, diodes, connectors, LEDs, and so on.


• We have projects all the time, and have plenty of boxes with unsorted components in low quantities, for each project.



• We currently don't keep track of our stock.


• When we have a need for components, we would just order or maybe take a look before order at Mouser, Digikey, Farnell etc...


• BIG ISSUE ::: When we need to pass an order, it would take at least 1 week for administrative reasons.

We have arrived to the point where we need to know:

• What is cheaper? Keep a big stock (keep track of it) or order components we need (constantly)?

Update: I will add that, we have recently bought several SMD resistor/capacitor kits, and this simplified our situation. If you have any other tips like this it would be great!

Answer

I'm going to disagree with others. No, don't bother keeping track of inventory. You are doing this for engineering, not production, so knowing the exact number of parts on hand is a lot less valuable than the time wasted keeping the system up to date, and the inevitable busywork when someone doesn't. Engineers need to be able to grab a resistor without having to fill out a form, even after the fact.

However, you do need to keep parts on hand. See my answer here for how we do it. That picture is quite old, and our parts stock is probably 30% bigger now, but the system is the same.

Instead of tracking inventory, keep a clipboard or a list in a computer somewhere of items that you are running low on, or wish you had. Whenever new parts are ordered, include the items on the wish list.

When you do order parts, get a few more than you need and put them in your lab stock. Usually buy to the next higher price break. For example, it makes no sense to buy less than 100 0805 resistors at a time. If you need three of one IC, buy 10 or 20. This is how items get added to lab stock. Sometimes when you buy one item, you realize you may have a use for a similar item and get a few of those too.

It also helps to standardize of certain parts. For example, there are many many small signal bipolar transistors that can handle a few 10s of volts, 100s of mA, and are reasonably fast with decent gain. In the absence of special requirements, I use MMTB4401 and MMTB4403 for these. We buy those a few 100 at at time, depending on where the price breaks are. Many other transistors would do, but sticking to a small number of jellybean parts when it doesn't matter simplifies your lab stock and ultimately production inventory.