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Flow and the metal fabricator: Making it visual

To manage the process effectively, you must first see the process

Figure 1
Visual indicators, like simple signs attached to material handling carts, show veterans and rookies alike where material is, and where it needs to go. Photo courtesy of Tim Heston.

It is the weekly scheduling meeting for a fabrication plant. Managers and supervisors from production, scheduling, material management, and other departments get together to discuss the previous week and the upcoming week. It is all too familiar of a meeting. Going through the agenda, they address the new orders placed. Business is doing well, but this is only the feel-good part of the meeting.

The agenda then turns to orders from the previous week, and things do not sound as great as they did minutes before. Orders missed their shipping dates, and now this week’s orders will be affected. Questions fly around the room, and suddenly this meeting starts to sound like the previous week’s meeting.

“When will the order ship?” “What orders will need to be pushed out?” “How long was the equipment down?” “I thought we already fixed that machine!” “Why did they not catch the defect earlier?” “Where are we at with the order now?”

Once people answer these questions, or in some cases simply assure their supervisor that they will get back with an answer, the solution soon follows: “The [insert name] department will need to work overtime this week to catch up.”

Many fabricators assume that the weekly scheduling meeting reflects how the flow of the shop is planned and sustained to satisfy customers. But is that really the case? The point of the meeting is communication. These meetings involve the communication of a plan and verification that the previous plan was executed correctly.

Unfortunately, this is where the communication starts and ends. The plan either fails to get deployed to the shop floor, or is deployed ineffectively. Even though a transition to a daily scheduling meeting may result in improvements, is that really enough communication to be successful?

Within lean environments, this is where visual management really helps. Visual management, or the visual workplace, is a system of communicating necessary information (the plan) to all levels of the organization while simultaneously communicating back to leadership when the plan failed.

When you can see product flow, you can easily see a plan being executed. When flow stops, you know something has not gone according to plan. When that happens, operators and leaders together can identify this immediately and team up to correct the abnormality.

One challenge with fabrication plants is the inability to see the process flow. Unlike mass production or assembly line operations, you really can’t “walk” the fab shop and see a product transform from raw stock to a finished good right before your eyes. That’s because typical fabrication facilities have disconnected processes in which orders are moved from one operation to another, often in different areas of the facility. In other words, product flow cannot be seen in real time.

This is why a strong visual management system can be so critical for a custom fabricator’s success. You could argue that visual management is actually more necessary at a high-product-mix fabrication shop than it is at a mass production facility (see Figure 1). Visual management allows everyone to see flow where the flow of product cannot easily be seen.

Figure 2
The visual management triangle illustrates the concept of effective group communication.

What Is Visual Management?

In her book Visual Systems, Gwendolyn Galsworth defines a visual workplace as “a self-ordering, self-explaining, self-regulating, and self-improving work environment … where what is supposed to happen does happen, on time, every time, day or night—because of visual devices.”

It is a straightforward definition of how we want our shops to operate. What is interesting about this definition is the word self, because it describes how a visual workplace is created.

We must ask who the self in this definition is. Is it the operators or leadership? In his book The Visual Factory, Michel Greif answers this question by defining the visual management triangle (see Figure 2), which illustrates the concept of group communication. In the age of ERP and MRP systems, organizations have transitioned from schedules on a wall to schedules in computers. In doing so, the “public interface” has been lost, and much-needed information to manage operations has become invisible to those who need it most.

When communication is visual, we see together, know together, and therefore act together. Effective visual management accomplishes the visual management triangle using the same visual devices. And the design of those devices becomes critical in establishing a useful visual management system.

Visual Devices

A visual device, or visual control, communicates how a task, work, or process should be done by establishing the standard for that task, work, or process. Making the standard visual allows everyone, operators and management, to see if the process is deviating from that standard.

The visual device delivers information when needed—immediately, just in time. A visual device should allow you to observe a process, machine, inventory, operator, or anything else and immediately see if the standard is being met. After glancing at a visual device, managers should know the current state of a process. This allows people to focus on where the current state is deviating from standard, rather than spending time determining if a process is meeting the standard in the first place.

The message communicated determines the type of visual device to use. These devices come in three general categories: indicators, signals, and controls.

Indicators are static in the sense that they never change (see Figure 3). For instance, painted lines on a floor are a visual indicator. They communicate where material or mobile equipment should be placed, or how traffic flows. General signage also falls into this category, as do labels for screw sizes and types in a tool crib. Signs and labels specify locations for materials, tools, and orders. Of course, people need to look for and see the visual indicators to receive their message. That is, they must be “found by the individual.”

Signals catch people’s attention. Unlike visual indicators, signals appear only when necessary. The stack lights on equipment communicate machine status and change color when the machine is in a given state, such as a breakdown. Like a stoplight or an andon board (status display station), visual signals will “find the individual” to get their attention and deliver the message.

Controls limit actions or responses. They not only communicate that action is needed, but also what the correct action is. A prime example is production cards, or kanbans, in a pull system that define how many parts should be made by what machine.

Figure 3
Visual indicators are static and can be as simple as lines on the floor, showing everyone where certain work should be placed. Photo courtesy of Getty Images.

Visual management makes use of one or a combination of these devices to manage operations effectively. Visual indicators and controls communicate what and how many are to be produced, and by what equipment. This in effect makes the production schedule part of the shop floor environment. These visual indicators and signals help people identify at a glance if the production schedule is not being adhered to.

This is the essence of visual management. Leaders should consider these devices as critical, and everyone should know that ignoring or misusing them—that is, deviating from the visual standard—will not allow the business to meet customer needs. If such deviation occurs, both leaders and employees should take action.

Managing Flow

The visual management system is something that each organization creates to help manage flow. In Creating a Lean Culture, author David Mann states that as part of the daily management routine, leaders have two responsibilities: (1) verify that a process is being executed as designed and (2) that the process is being improved.

Here, let’s analyze the first responsibility: verifying a process is executed as designed. Consider a fabricator where production control sets a schedule based upon a designed flow or capacity of an operation, be it machining, stamping, bending, cutting, or welding. Barriers to flow often cause the misses discussed during the weekly production meeting.

To best meet the production schedule, fabricators must manage the process and not the schedule. If the process operates as designed, then the production schedule, theoretically, will always be met. This assumes that other abnormalities, such as overbooking and mistakes in estimating, do not occur. Regardless, those are outside the control of production. For production, the necessary visual devices help people on the floor manage flow.

Consider the flow of material. Linking previously disconnected operations, visual devices such as signs and lines on the floor make the flow visual even to the untrained fabricator’s eye. Designated material staging areas and first-in-first-out (FIFO) lanes are common examples for managing material flow in low-volume, high-mix operations.

Simple lines and signs help answer questions like “Where does this completed order go after plasma cutting?” and “Where is the steel for my next order?” A rookie fabricator looks for a line and a sign, and he knows immediately where to place a finished job and where to retrieve raw stock for the next order.

Of course, for this to work well, both production and material management departments need to operate within that visual management. For instance, they must make sure that materials are where they are supposed to be. If a rookie operator sees a sign pointing to a location where raw material should be but isn’t, then the visual device really didn’t help the rookie operator at all.

Those fabricators fortunate enough to have highvolume part families can manage operations with a pull system. With visual devices and signals, inventory can be monitored and production triggered only when needed, or when inventory reaches a level where a production kanban is deployed. This essentially links the disconnected parts-production departments to the downstream operations. Parts production, like laser cutting and bending, now produces parts only at rates that downstream assembly and other operations need.

Regardless, whether you have a high-volume, low-mix or low-volume, high-mix shop, visual management should define the designated areas for storing and transferring material. People should not move or transfer orders unless those orders have a designated area to go to.

Figure 4
This day-by-hour production chart documents volume by hour and records any deviations from the target volume.

The Flow of Capacity

Because the fabrication environment tends to be a custom, build-to-order, or similar low-volume, high-mix operation, most see the overarching fabrication process as having fluctuating flow. This is true when comparing it to mass production. However, if you interpret flow as capacity, you may be able to take a different approach to manage that flow.

Say you have a press brake operation that has a high mix of products, with volumes high or low, and yet the size of parts does not vary greatly from one order to the next. In this case, maybe the fabricator was fortunate enough to group together like parts or parts with very close cycle times so they can be produced in the same operation or setup.

Each operator should take a given amount of time to complete an order (total parts multiplied by cycle per part plus the setup time) before moving to the next order. Because of similar cycle times, the production schedule is built based on the total number of parts that can be produced by that operation over a shift.

This would result in equal volumes of parts required per day, much like a mass production manufacturer. Like in mass production, a visual management system should be in place to monitor progress each hour throughout the day. This is called a day-by-hour or hourly production chart (see Figure 4). Both operators and leaders may set a given volume of parts to be produced each hour as a target to meet the schedule. The hourly volume is documented on the chart, and any deviation from the target volume can be identified and addressed, hourly.

Now consider the same scenario but this time in a high-mix, low-volume operation in which the size of parts varies greatly from one order to the next. The operator still should take a given amount of time to complete each order (again, total parts times the cycle time per part plus the setup time) before moving to the next order.

This time the production schedule is built based on the total time per order and what can be completed in the work hours of each day. In this scenario, scheduling could require 5 orders for Monday, 10 orders for Tuesday, 8 orders for Wednesday, and so on.

Unlike the previous example, the visual management system should monitor the progress of the operation by each order, not time. This is called a day-by-order chart (see Figure 5). Instead of managing volume by time, leaders and operators manage time by orders. For each order, employees can record actual completion time next to the estimated (target) time on the chart. Comparing these times allows operators and leaders to better manage process flow and address abnormalities earlier.

Flow of the Workday

Finally, what about people and the flow of their workday? What should the operator be doing during and between each cycle or order? This hinges on how effective standard work or standard operating procedures (SOPs) really are. Quite often these documents are written for quality systems and not for the benefit of managing the operation, outside of training. Here, visual management can help make standard work and SOPs very effective.

A standard describes how tasks are to be completed to meet the design of the process. Leaders and supervisors must verify that operators are performing tasks according to the standard and correct behaviors that cause deviations from that standard. Similarly, operators must learn the best current practice of performing a task and adhere to that practice to be most efficient at their job.

Of course, if the standard work isn’t posted and communicated effectively, people will deviate from it, and inefficiencies will ensue. Hiding these documents in a binder makes them ineffective. If no one sees them, they can’t help people manage flow or identify problems with that flow.

Visual management helps everyone see the flow. The easier it is to see the flow, the less resources and time it takes to determine if the flow is correct. This allows everyone, leaders and operators, to see incorrect flow, know it is incorrect, and act—together. After all, no problems should remain hidden.

Figure 5
In this day-by-order chart, employees record the time it takes to complete each order. The actual time then can be compared with the estimated time.