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November, 2024
In academic careers we mark time in stages. Pre-doctoral and post-doctoral. Pre-tenure and post-tenure. In reality, you’re very much the same the day before and after you defend your thesis, and the day before and after you get a 'permanent' job.
For me, the dividing line is clear: pre-kanban and post-kanban. That's the shift that changed everything, because it was radically different on either side of that line.
Did you take the last one?
< Lord of the Flies, 1963 >
Before kanban, I had FORO (Fear of Running Out) which is a serious disease in many laboratories. You open a box, reach for that reagent, and— nothing. All the hours of planning and progress evaporate, along with your trust in humanity. Left unchecked, FORO becomes Lord of the Flies. Under the stress of constant resource shortages, former teammates become rivals, distrustful and paranoid.
Incredibly, some lab managers promote this behavior by acting as Chief Hoarding Officer. Cases arrive in multiples of 10 ("I found a good deal"). 20-year-old polypropylene tubes ("We'll use them someday") and 10 kg buckets of NaCl ("It never goes bad") are sources of pride. In one lab of my acquaintance, the FORO was so extreme they hid 'backstock' supplies behind 5 levels of secrecy:
Level 1: Everyone.
Level 2: Everyone except the undergrads.
Level 3: Lab Manager and Senior Postdoc (the "Chosen One").
Level 4: Lab Manager and PI.
Level 5: Only the PI.
But where others saw safety, I saw failure— five heaps of inefficiency. Business school taught me that inventory is waste. Lean management favors cash and keeps inventories near zero. Toyota doesn’t seek inventory, nor does Baxter or Xerox. Yet research labs are overflowing with boxes because most managers lack business acumen and PIs accept hoarding behavior as normal.
That’s where kanban come in. They're the antidote. They rescue sanity and save the collaborative spirit of scientific discovery. In this post we'll examine two kanban systems for inventory control. One is a costly method used by critical facilities like pediatric surgical centers. The other is a budget-friendly method accessible to any lab for under $100.
Expensive Version: Pediatric Surgical Supply
If you had to devise the ultimate FORO-prone logistics chain, it would have to be that which ends up in a baby's thorax. That's the context of a pediatric cardiac surgical unit and their key distribution center: the supply room. This room is packed with miniature catheters, pacemakers, stents and heart valves– all critical to the survival of tiny, helpless patients. Run out of these supplies? Hospital administration would never allow it.
To ensure they’re always stocked, these rooms employ a "pull" inventory system. In the most advanced facilities, every item has an RFID tag. When staff take supplies, overhead scanners automatically update the inventory as they walk away.
When demand causes inventory to fall below a critical level, computerized orders flow out to the vendors. New items arrive, get tagged, and are shelved ready to go. Babies are saved, parents are grateful, doctors are proud and the hospital reaps money.
Budget Version: DIY Kanban for the Research Lab
No money for RFID tags? I thought not. Here's how to accomplish something similar using kanban.
In Japanese, kanban (看板 ) means 'sign' or 'billboard'. The kanban system was developed by Toyota in the late 1940s and remains a key component of their 'lean' manufacturing philosophy. It focuses on reducing waste (muda, 無駄 ) by allowing front-line staff to visualize the state of work and manage inventory. And let me tell you, my friends, it is a game-changer. Fact: I started with 4 kanban, and less than six months later ended up with >40. It's cheap, crafty and fun– so much fun you'll want to throw a kanban party.
What You Need
scissors ($10.50) or paper cutter ($22.00)
colored index cards (pack of 100, $2.85)
label maker and/or laser-print file-folder labels (box of 3,000 = $24.00)
lamination machine with heat-seal pouches ($39.99)
1 or 2 clear plastic brochure holders, table and/or wall mount (2 x $2.50)
Velcro tabs, rubber bands, or string to attach kanban to various containers ($6.50)
TOTAL COST before TAX = < $100
Making the kanban
1) Gather the information needed for each item (product name, catalog number, vendor, quantity, etc.). 2) For each kanban make two sticky labels:- The front label announces itself. Grab the user's attention!
- The back label lists the desired information needed to re-order the product.
Distributing kanban to multiple boxes, cases or kits
Kanban work best when there is a centralized stock or 'root stock' for each item. For example, everyone can have their own stash of rapid-flow filter tops, but should take these items from a single root. Thus, the root is any location where all new cases are kept and and the kanban put into them.
*CRITICAL STEP* All cases are cut open, then dated and labeled sequentially: 1 of N, 2 of N, ... N of N. If your manager stores inventory by shoving new boxes into closets on top of old boxes, or hiding multiple boxes across the lab anywhere they might fit, this system will fail. Ditto if your staff can't read labels or count to five. It's a team effort to achieve this level of planning, but the benefits are considerable.
Once the root stock is organized, the kanban can be placed anywhere in the series. This is called the trigger level. Ideally, the trigger level is sufficient to cover the lag time, which is the time between placing an order and new stock arriving, plus an arbitrary safety factor, which is a fraction or multiple of the lag time (e.g., 0.5x or 2x). At the end of this page you'll find a detailed example. But for starters, just place each kanban at the point where 50-75% of the root stock is consumed.
Distributing kanban to other types of items
This root stock is under the sink. A rubber band attaches the kanban to the last gallon.
This root stock is in a -20C freezer bin. Buy two bags of PCR enzymes and place the kanban in the second one.
This root stock is in the chemical room. Buy bottles in pairs. Attach the kanban to bottle #2.
Returning the kanban
Now sit back and wait! When a kanban is discovered, the only action necessary is to place it in the nearest return. In this lab I set up 2 returns: main bench and stockroom. I used plastic brochure holders from Office Depot and added my own décor.
Twice a week I’d visit the returns, pick up the kanban and place the necessary orders, keeping the recycled kanban my desk.
When the orders came in I would open all the boxes, label them sequentially and put the same kanban back in at the 50-75% level.
No more checking the levels of boxes in the stockroom or finding empty boxes like this ever again. Problem solved!
In conclusion, kanban are cheap, cute, and people love finding them. Best of all, it requires no human or computer interaction to initiate an order.
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Frequently-asked questions
Can I put these kanban into cold-storage areas?
When laminated using the method described, these kanban held up in refrigerators, cold rooms, -20C and -80C storage areas for at least a year.
What can I use in place of a lamination machine?
Laminating alternatives include heat-seal bags (which many labs use for hybridization and blotting applications) or two pieces of clear packing tape sandwiched sticky sides together. Either option will give your kanban that extra protection.
More on lag times, trigger levels, safety factors & order quantities
If you don't have a good estimate of these variables for your critical lab items, don't feel badly. The typical manager– myself included– is more likely to set order quantities based on psychological safety rather than scientific evidence. That is, we use our painful memories of past disasters and weak intuition about future demand rather than consumption rates and lag times. With practice, however, you will find the perfect level using observation and logic:
Example: We use ~1 case each week, and it takes 1 week's lag time to get a new case from the vendor. So the absolute minimum trigger level is when 1 case remains. Let's add an additional week as a safety factor. Now lag time = 2 weeks. Knowing this, we should re-order N cases whenever there are 2 cases left. This stock will last 2 weeks, by which time we should safely have our N cases.
Finally, how many units, N, should you re-order? Clearly, the minimum order is that which replaces the trigger level. Your maximum order depends on 1) available space, 2) how cumbersome it is to place orders, 3) the cash discount, if any, for ordering in bulk and 4) how much liquid cash you want to freeze in the shape of supplies.
Most managers will consider the first three principles, but few appreciate the fourth. I repeat: inventory is waste; cash is king. Why turn $1,000 cash into a pallet of syringes? Once bought, syringes can't be turned back into cash— or anything else— very easily. Only cash handles the unexpected, like sending someone to a Gordon Conference or fixing a broken centrifuge. It’s baffling when managers boast about saving money this way. What they’ve really done is freeze money with consequences unknown until the future arrives. And we all know the dangers of extrapolation. So freeze enzymes, not assets. Stay liquid!
If you liked this blog post, here's another: Six Strategic Pearls for Prospective Grad Students
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