Cellular Manufacturing: What’s In a Workcell - Allis Roller: precision machined parts, welding, and services

• Jun 24, 2019
• cellular manufacturing, lean manufacturing, machined parts manufacturing, machining, manufacturing, turning, welding
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Why is manufacturing going cellular? Because it’s a useful tool for reducing waste and meeting lean manufacturing goals. Here’s how it works: workcells organize machining processes into an assembly line that reduces waste and opportunities for mistakes. At Allis Roller, when feasible we design custom cells to achieve continuous flow for optimal safety, quality, and throughput results.

How Cellular Manufacturing Helps Machine Shops Stay Lean

Allis Roller employs cellular manufacturing because it allows us to improve safety, cut down on waste, and improve quality. We try to focus on what is needed, when is needed. Continuous or one-piece flow supports lean by focusing on two things. First, a production cell contains everything needed to produce a part, and nothing more. Second, nothing proceeds to the next process step until it is complete and correct. This approach results in fewer errors, improved quality, and higher overall efficiency as all required information, materials, tools, and equipment are in place and available.

When possible, we try to optimize process flow by grouping machines or operations in a cellular configuration. The goal is to reduce lead time and operating cost, while increasing labor flexibility and labor utilization.

Each of these workcells is designed with a takt time and a “family” of similar parts in mind. At Allis Roller, whether a customer wants 5 pieces per day, or 500, our lean manufacturing engineers structure the workcell to meet customer demand “takt time.” We aim at producing exactly what’s needed, when it’s needed. The challenge is grouping like parts through the machining cells so we can balance the demand and optimize throughput. We may not use each machine tool for every part we run through the cell, so balancing the process times is critical to throughput.

Continuous or one-piece flow tends to be leaner than batch manufacturing because parts are constantly moving instead of piling up between processes. Our goal as a machine shop is to remove, reduce, and eliminate non-value-added activities, while also improving activities that add value for the customer. The steady flow of cellular manufacturing helps us accomplish exactly that by helping to reduce handling and transportation, reduce errors, and control waste.

How Cellular Manufacturing Practice Works at Allis Roller

Cellular manufacturing can be enhanced using proven lean tools. At Allis Roller, we use the following tools to enable flow in our workcells:

• Standard work – Optimizes operations by ensuring the task/operation is carried out consistently. Standardizing work helps use people, materials, methods and machines effectively.
 
• Poka-Yoke – To prevent mistakes from taking place in the first place, we try to establish a mistake- or error-proofing procedure or device to prevent a defect from occurring. Some types and examples include guide pins of different sizes, error detection devices or alarms, limit switches, counters, and checklists.
 
• 5S – We thrive to create and maintain an organized, clean and safe work environment in which the employee and company can deliver and achieve high performance. A 10-minute task should not take more than the required time because we don’t have the correct material, tool/equipment or information.
 
• Continuous Flow – In a cellular environment, product does not proceed to the next process until is complete and correct. For this reason, a cellular environment aids in having everything you need where and when needed. We focus on what is needed, when is needed.
 
• Total Productive Maintenance (TPM) – TPM focuses on the operation and uptime of the equipment with the goal of preventing breakdowns and defects. The TPM attitude is that “we are all responsible for our equipment” instead of “I run it, you fix it”. Operators are given a larger role, and training, to support the maintenance and operation of the equipment. Ultimately, if the equipment doesn’t work properly, we all suffer the consequences of unhappy customers and lost work.
 
• Change over Reduction (SMED) – SMED focuses on reducing set-up and changeover times between jobs. Change overs are imperative to running a job. Unfortunately they don’t add value to the product, and for this reason we concentrate on eliminating or reducing the time it takes to set-up a job. Reducing the setup time additionally allows more flexibility in our production scheduling because we don’t need to be as concerned about non-value added setup time.
 
• 8 Wastes – Waste exist in many forms: overproduction, waiting, transporting, over processing, inventory, motion, defects, and waste of human talent. By reducing these,  Allis Roller is able to reduce costs and increase flexibility.
 
• Visual Management and Controls – A picture is worth a thousand words. Visual management incorporates visual controls and process layouts to make it easy for anyone in the production area to easily spot an abnormal or unusual situation. Examples of visual controls are visual work instructions that show how to do the job or how items are used, showing where things are stored, indicating when a station needs help (ANDON light), and mistake-proofing the operation (poka-yoke).
 
• Production leveling – Similar to a production line, production leveling is the balancing of work at each station so that there is no idling or overworked stations within the cell. The idea of leveling is to produce goods at a constant rate so that you can allow further processing to be carried out at a constant and predictable rate. Elimination, reduction, and understanding of the bottleneck processes is critical to maximizing throughput of the cell.
 
• Supermarkets – A supermarket is another tool in the lean toolbox. The objective of the supermarket is to reduce material handling time, transportation waste, to visually asses inventory status, and help level products that have very different cycle times. The key of a supermarket; is the fact a visual signal is generated to replenish a product the moment it is taken from inventory. A supermarket aims to keep all parts in stock, while at the same time avoiding overproduction. There should be some kind of a supermarket in front of the cell bottleneck to ensure that the bottleneck process is never waiting for product.
 
• Kanbans – Kanban is a visual scheduling system for lean and JIT manufacturing. Kanban is a “visual aid” tool designed to reduce the idle time in a production process. The main idea behind the Kanban system is to deliver what the process needs, exactly when it needs it.
 
• AndOn Lights – AndOn Lights are visual aids used to communicate when a station requires additional help. They are most effective when the entire team is cross-trained so people move to whatever part of the cell may need extra help.

Using tools like these, Allis Roller has maximized the benefits of cellular manufacturing in our facility, and the proof is in the numbers. For example, we were able to improve the rate of production at one of our fabrication cells by 24% after utilizing some of the lean tools described above. 

To learn more about how cellular manufacturing keeps Allis Roller continuously improving, connect with one of our lean manufacturing experts here.