Why do we hold stock? - Generic, consumable items that are used regularly (heat shrink, cable ties etc) - Prototyping. We keep a selection of common electronic components on hand so that circuits can be made or modified without waiting for parts to be ordered - Emergency break downs. Some of our customers can't afford to wait for now components to ship. In these instances a good enough alternative that is on hand is valuable. As an example we have a small number of VF drives on hand. We don't keep every size but have a small selection that can be used to get a machine running in a hurry. Ideally we want to have one location for every category of item that we keep in stock. This can be difficult for various reasons - Lots of values - Lots of types of the one category - A wide scale of items in a category Categories of Storage === - Complete set of most useful type - Reduced set of next most useful type - Miscellanous - Overflow - Used Generally we want to organise the stocks according to the following buckets - A set of the most common example that spans most applications. For resistors this is the 7 decades of E12 values for 1/4 watt size. - A limited set of the next most useful parameters. Large resistors in the 5-12 watt range - A bucket for micellaneous items. These are for new items that have a specialised purpose (high precision resistors, aluminium case resistors etc) - An area for overflow. New items that don't fit in the existing storage area (should be kept to a minimum, might need to be downstairs) - Second hand. This is similar to miscellaneous in that we often come across rare and expensive items in equipment that is going to scrap. It is important that this doesn't infect our storage of new parts though New parts should have a traceable supply chain. We should know - how old they are - where we got them from - what their parameters are (datasheet) - how much they cost - where to get them from when we run out Everything that we currently have could be grouped into the following categories - The right stuff in the right place - The right stuff in overflow - The right stuff in unsorted - The right stuff in multiple places Steps to take when planning a re-organisation of an area of our stocks === - **Gather all of the existing stock so you can see the range of types, sizes, ratings, colours etc.** This shows the range of what we have used in the past. (keeping in mind that the current stock is the items that we haven't used. Sometimes they are an example of what we don't need)* - **Identify the manufacturers.** Pick a good data sheet or catalog and find the full range of available items. *This allows you to see all of the items that may need to be stored at some point in the future. You may think that we will never need a certain size or type but if someone buys them in the future your storage solution needs to have somewhere to accomodate them. - **Find the suppliers and look at what they keep in stock.** This gives a good indication of what is typically used by the industry. There may be 100 different sizes of heatshrink available but the 25.4mm category will have 38 products available and the 25.7mm category will likely only have 1. - **Pick the characteristics that will define your storage choices** For Resistors it is Mounting Method, Power Rating (size) and then Resistance. So we have sets for through hole mount and surface mount. Then inside each of them we have 1/4 watt, 2W, 5W (0603, 0805, 1206) etc. Then we pick values based on the [E Series](https://en.wikipedia.org/wiki/E_series_of_preferred_numbers?mc_cid=26410f6d40&mc_eid=56f05730b5) for the resistance. - **Select the range of items that we should have in stock** We don't need to hold everything in stock. Items that are too specialised or used rarely that are available from trusted suppliers don't need to be in stock. We normally want a broad selection of the most typically used variations. So we don't want every size available, we want the 8 sizes that are typically needed. - **Plan out the number and size of the containers that you will need to hold all of the stocked items.** You need to have enough containers to seperate the typical number of Notes, - Don't fill the available space with storage containers. You are likely going to have to adapt the storage area over time. You won't know in advance what you are going to need in the future. - Try to keep everything of the one type of component in the one area. This isn't always possible. - You will need a container for "Miscellaneous". These will be specialized items that you won't know that you need until someone is looking for a place to store them (teflon heat shrink). - The top and bottom values in your range are going to have to be able to contain all outliers. If you have 50mm as the largest size of heatshrink someone is going to order 100mm heatshrink and need somewhere to store it. - The size of the containers should indicate how much of that item we want to keep in stock. If someone looks at the container and sees that it is 3/4 empty they should reasonably think that they should order some more. - The standard amount of an item that can be economically purchased should half fill your container for it. You don't want the container to overflow everytime you purchase more. - It is useful to have an overflow container as a catch all. This way someone looking at putting random parts away can do so quickly and it can be cleaned up later. (this is dubious advice, DRP)