Material handling, at least in the machine centers I have been around, is a bastard child when process improvement people come around. Even the neat and tidy plants still use those ugly, difficult to use vertical racks. Or those tall two sided racks that look like power poles. Or the metal stays in the box on the floor by the machines. I have rarely seen elegant solutions.
So today I want to tell you about the solution I devised which is elegant, front loads most of the material processing, provides a traceability mechanism, and removed most of the intermediate handling by personnel. Among other things, it is typically a system any half competent machine shop or similar can implement themselves. So stick around and I’ll tell you about how the idea and the process came about.
Material storage at this facility was the same as thousand other machine shops. Vertical racks covered one wall, pine shipping boxes litter the production floor, the horizontal standing racks eat up most of the remaining floor space in the stock area.
Daily, the stock attendant man-handles steel bar, pipe, or aluminum out of the rack, cuts to size and carts it to the machines for the day. Typically this activity occurs at the beginning of each shift (there were three) and intermittently throughout the day depending on consumption, order changes, change overs, you name it.
Common issues from the status quo
- Smashed fingers, tweaked back, other minor injury from material handling
- Wrong material pulled and cut, machines break inserts and tools half the shift until someone figures it out
- Not enough material was cut or there was lots of scrap and the first two issues show up again in some flavor
Additionally, the stock area was jammed full. Production output was increasing but there was no where to put the additional material. It was staged in some open places in the facility. Then it had to be carted over. Sometimes it got mixed up and queue standard material problems. So no one loses track, here are the problems raw material handling was causing.
- Waste from wrong material on a machine
- Time
- Material
- Consumables
- Waste due to excessive movement of stock material
- Motion of people and material
This problem was (mostly) solved using flow charts. Simple, any 3rd grader can draw flow charts. Other tools were utilized during the effort and I will make a list later.
We flow charted what happened for material to come in be processed and go to a machine. In doing so, the primary required activities necessary for the material to be ready to use were identified.
- Receive
- Store
- Pull
- Cut
- Distribute
Following this determination, each area was assessed for potential problems. If you want to flex your vocabulary, we were looking for failure modes (good old FMEA) at each step which could result in the previously stated problems. Here they are, not quite in perfect detail, but enough to provide relevant understanding.
- Receive
- Incorrect material
- Incorrect quantity
- Incorrect size of material
- Store
- Stored incorrectly
- Marked incorrectly
- Lot number (when relevant) not recorded/lost
- Pull
- Pull wrong material
- Pull wrong size
- Pull wrong quantity
- Cut
- Cut to incorrect size
- Distribute
- Wrong machine
- Incorrect quantity to machine
After some thought I had the first revelation of this project. Steps 1-4 could likely be done right away. Ordered material was designated for a known product. So the material type, stock order size, quantity, and cut length were known before it arrived. The catch was how to store the material. I couldn’t justify the “do it now” of these sections without a specific solution for #4: where to put the material.
Revelation number two that made this solution the success story it is. After exhaustive searching online for metal storage racks which resulted in finding nothing other than what was already on hand, I designed one that met all the process needs.
The process needs:
- Allow for cut to size and simple storage
- Facilitate material identification
- Simplify transport
- Maximize space efficiency
The physical solution is a custom designed metal rack. Made of box steel and flat iron, from the front it looks like a “U”. The box steel on the bottom of the U allows it to be forklift pickable. Cutouts in the side allow it to be picked from the side as well. Each rack was ~24”H x 24” W x 48”L. 4 could be placed under a standard heavy duty pallet rack. A 16’ HD pallet rack could be configured to hold six shelves of four racks, with one row in the floor under. Shelf spacing is set at 28” to allow for picking with a lift. We may have set them at 30”, I don’t recall. The “front” of each rack had a hole drilled at the top and a sheet protector zip-tied on. The purchase order data was put in this pouch.
The process was amended as such and included use of our spectrometer gun to verify material.
- Receive and verify material is correct dimensions and type, acceptable orders have the order copied and put in the open rack’s sheet protector.
- The material is then unloaded and based on the destination product, is cut to length and placed in the rack.
- Once the order is completely cut, the rack is moved by forklift to an open location in the storage racks. High up for pipe or aluminum, and low for steel or large quantity orders.
- When a job required material pulls, the forklift would pick the rack and place it in a central location in the shop or near the appropriate machine.
- Operators could then come to pull material easily and could verify the material via the attached records.
There are so many elements of this process in most shops this system makes better I don’t know where to start. So I’ll go with the safety one. After cutting, the next time the material is handled with oft squishy fingers is when it gets put in the machine. No one is pulling it off a huge rack with other material in the way. It isn’t getting pulled from the vertical rack full of sharp ends and the wrong material.
Space efficiency here is bonkers. If we assume a 20” square space to put 1” steel bar cut to 48” lengths and ~0.05” space between them one rack can hold ~1,200 feet of bar stock. I don’t believe I ever saw an order for 1” bar even half that size. So if we consider the potential for ordering 300’ of 1” steel, delivered in 12’ bars, the difficulty handling this and the raw space to hold it uncut is pretty awful. Yet nearly everyone still does this.
The shop had at the time three 16’ high heaven duty pallet racks. Each rated for something like 48k pounds or something. If we assume six shelves plus the floor underneath we get 28 racks per shelf and 84 racks. The unrealistic potential here is ~100k linear feet of 1” material can be stored in a space 24’ W x 20’ H x 30’ D. We had the picking or on service shelf in the shop too and it would accommodate an additional 16 racks for on service use.
It took a few weeks to build all the racks and a another week or so to get the process down and the existing room cut and racked. The elegance (yes we can say this about a machining center stock room) of that space when it was all done would blow your mind.
Problems that disappeared right away:
- Wrong material on the machine
- Minor handling injuries
- Insufficient amount of material for production run
There are other, additional mechanisms this could be improved. The racks could be color coded for materials (aluminum, 15-4 SS, 17-5 SS, etc.), the racks can be made wider, shorter, taller, as needed. We did 2’x2’x4’ as it served our needs. You could do this but add a divider inside and keep two materials inside each one. Instead of a picking shelf each on service could be placed at the running machine. The racks could be designed to stack with each other.
This is one of my favorite solutions because it fixed so many problems at once. The biggest one though, if you didn’t notice is related to wrong material on machine. Each product is designed to use a specific material. The programming, inserts, tool settings rely on correct setup with the correct material. Otherwise you are breaking bits, fighting the program all shift, and potentially making hours worth of garbage as the wrong material may not be compatible with downstream processes. It is uncommon to have a single action solve a problem with this amount of downstream impact and potential savings. Correcting this was not the instigator here though, the stockroom space issue was why the analysis even happened.
The lean and process improvement tools or concepts employed to reach the solution.
- Flowcharting
- Five why's
- FMEA
- Cause and effect diagram
- Rule of constraints
- 5S
- Waste elimination (muda)
- Overall equipment effectiveness (OEE)
- Poke-yoke
- Standardized work
- Visual management
If you found this interesting and would like to know more about this system I would love to show it to you. Especially smaller shops where space is at a premium, this could be a game changer for your material handling. Even if you only use it for 20% of your bar stock, the impact is immediate and visible.
I have to mention another component here. Think outside the box. The industry for storage has some really good solutions. Many of these are based on old ideas. This solution came about with some original thinking and a laser focus on process needs.
My Start. Somewhere. System is all about finding your process needs so you too can find solutions that fit you. Reach out, I’d love to talk about your problems.
