Lean Manufacturing in a Job shop

Lean Manufacturing and job shop are practically opposing philosophies. In a CNC precision job shop, standardization can be difficult and costly. At Preece Machining & Assembly we have been dedicated to finding a way to implement lean principles into our precision CNC job shop.

What is a Job Shop?

A job shop in this context is a shop that performs machining for its customer essentially selling machine and setup time. Contrasted with a shop that makes its own products, job shops can be cursed with inefficiency. This inefficiency stems from the fact that every day a new job requiring new tooling, new programs, and new setups comes through the door. This is essentially where quantity breaks come from. The time it takes to set up, program, proof out, and manufacture one part is costly. When a production run occurs, the customer is still paying for all the same tasks, but the total is divided by the number of parts ultimately lowering the unit cost.

What is Lean Manufacturing?

Lean is essentially eliminating waste. Wasted movement, wasted brain power, wasted space are all paid for by the customer. In a CNC machine shop that has not implemented lean, the customer is paying for non-value-added tasks. When our customers purchase parts, they can rest easy knowing they are not paying for an employee to walk around the shop looking for a tool. Our customers can come to see our shop and have confidence that our CNC machine shop has the procedures in place to produce parts as efficiently as possible. Lean is the practice of constantly improving a task to make it easier for employees and ultimately cheaper for customers.

Lean In Our Precision CNC Job Shop

Tool Crib Implementation

We can’t control the kind of work that comes through the door of our precision CNC machine shop. What we can control in the technology that aids us in making your parts! Preece Machining & Assembly is constantly investing in technology that gives us a competitive advantage. For example we love investing in new cutting-edge tooling. But struggling to find that tool when you need it is NOT lean and does NOT add value to our customers. Tool crib management was an obvious lean improvement we could implement to get more out of our shop.

We looked at the cost of not having a tool when we needed it. This usually meant a machine waiting for the tool to get in, employees spending time looking for a tool, or work on a project stopped while another project was subbed in. We invested in a tool management system that ensures we never needed to wait for a tool we should have on hand. Once a tool is used by a machinist the system adds the tool to the “out” list. If this tool is not replaced it is auto ordered. We also can track usage of tools and paint a picture of tool life based on how many times it checked in and out of the system.

Another added benefit is we were able to standardize our tooling. This lets us collect data on each tool and continue to optimize it for better performance. Bonus: our costs associated with purchasing tools, managing the tool, and admin costs have decreased significantly.

ERP Implementation

Finding areas to implement lean in a CNC job shop can be challenging. To be successful you always need to be looking at the consistencies in your shop. For example, every job at Preece Machining & Assembly gets a traveler assigned to each work order. Multiple people need access to these travelers as the job moves from one department to the next. How much time is wasted by employees walking a traveler from the saw department to the programming department to the milling department and finally to the inspection department? Over the course of a year hundreds of hours are lost at the very least. We want our employees using their time to come up with new ideas, not running all over the shop delivering travelers. We have implemented an ERP that allows us to have digital real time travelers for every single work order, eliminating the wasted motion of looking for a traveler and walking to deliver it.

Aerospace machine shops usually conform and are certified to standards like ISO9001 or AS9100. But let’s face it – in most cases the paperwork trail needed to be a cutting-edge aerospace machine shop is typically the opposite of lean. Our ERP has changed this for us. We consistently complete the needs of AS9100 with less work than we did before. One great example of this is material tracking is seamlessly linked to every PO and COMPLETELY digital. Every job has a digital copy of the material cert, first article inspection, and certificate of conformance linked to each work order.

Lean improvements do not need to be grand process changes that net hundreds of hours in efficiency gains. Lean improvements can be small changes to current practices that enable better visibility into the life of the shop or change the number of clicks it takes on the computer to complete a task.

Kaizen Foam

Kaizen foam is a foam product that easily lets users create shadows and specific cutouts for tools and necessary items. This might sound like over processing but the ability to tailor a work area to only contain the required tools reduces clutter and increases efficiency. Our CNC machine shop has implemented this lean process across our shop and has seen huge gains in productivity. As we progress in our lean manufacturing journey, we get the opportunity to precisely hone each CNC cell to make a better experience for our employees and a more profitable result for our customers.

We have found that small time investments like Kaizen foam pay dividends. Shown above is an example of a foam cut out on one of our milling machines. There are spots for the tools the machinist needs such as calipers and micrometers. We found that having the tool in the exact spot has multiple benefits such as: No clutter or random items are left on this shelf, in addition to this we have been able to track specific tools to specific machines for In Process Check Info. Meaning that we know if the part was built on MILL01 that calipers 1001 were used for in process inspection. Looking clean and the ease of use are practically a bonus compared to the other benefits.


Implementing lean principles in a job shop is a challenge and not something that can be done overnight. The benefits of working with a Precision CNC shop that takes lean seriously can have a huge impact on your bottom line. Preece Machining & Assembly takes advantage of every opportunity to implement lean principles to be more competitive for its customers and to provide a great place to work for its employees. If you’d like to see what the difference a lean shop can have on your bottom line request a quote from us today!

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