Maximizing Your Productive Welding Space

Designed on the principles of lean manufacturing to reduce waste and improve workflow, robotic arc welding work cells can provide accuracy, reliability, versatility, and speed for many industrial applications spanning diverse industries.

While some manufacturers would argue the most efficient robotic work cell on the market is the one with the smallest footprint, there are other factors to consider. Which leads us to the question: what is the most efficient use of valuable floor space?

In order for manufacturers to gain maximum return on investment (ROI) over a given payback period, it is imperative to use the most efficient work cell possible for handling a given application and part type. Recent buying trends suggest that the purchase of a larger robotic work cell with additional robots can be a more productive solution for a company to increase throughput and improve product quality, fulfilling labor shortages and meeting customer demands in the process.

While many Asian-based manufacturers stress a robotic work cell with a small footprint is best, companies in the U.S. have generally been less concerned with floor space. This mentality is changing, however, as manufacturers seek to fulfill initiatives for increased productivity.

Yaskawa makes a variety of standard welding work cells, which are part of the ArcWorldseries. These cells can be used to illustrate six factors that contribute to floor space productivity. In turn, these factors can also help explain recent buying trends and evaluate the driving motivator for getting more productivity from factory floor space.

Six Key Factors to Consider:

1. Part Area
   The part area is simply the space that is needed to support a product. For example, an automotive seat supplier has an obvious size difference between recliner brackets, front seats, and 60/40 split rear seat frames for sub-assembly. Having enough part area to effectively and efficiently produce quality parts with tooling is key. Positioning the parts is also a factor. If the part needs to be re-oriented, it will need a larger three-dimensional volume.
2. Work Cell Area
   This refers to the size of the entire work cell footprint, or how much floor space on the factory floor the robotic system encompasses. Manufacturers may view smaller cells as a more efficient use of floor space. While the footprint of the cell is a valid concern to consider, choosing a robotic system based on footprint alone is not ideal. Likewise, single-station work cells should be evaluated as a pair when comparing them to a two-station cell.
3. Safety Area
   An open space, where an operator must vacate during positioner indexing to be compliant with safety regulations, is known as the safety area. Some manufacturers will customize a robotic work cell with roll-up doors to minimize the safety area space. Suspending part bins for smaller parts inside this area helps utilize this space and improve ergonomics.
4. Operator/Parts Storage Area
   The operator area refers to the space where the operator grabs or places parts into the cell tooling. Cells with safety space can potentially crowd an operator with part storage, which would require a single station work cell to be equipped with a wider aisle. Single station work cells are sometimes placed opposing each other, so the operator loads one and then services the cell on the opposite side of the aisle.
5. Robot Quantity
   The number of arc welding robots—or “arcs” referring to working torches—in a work cell is also paramount when choosing a robotic solution. Adding a second or third robot can nearly double or triple welding production with little to no impact on floor space. This is increasing the “arc density” of a given work cell.
6. Cost
   The price of the work cell is considered at any stage of the design and implementation. Many times, the robot is a smaller percentage of the cost when positioners, cell controls, and tooling are included. Other items, such as laser sensors, could also increase cost but improve cycle time. A customer’s part and throughput requirements will dictate how much they may value these cost-adding features when creating an extremely efficient cell.

Application

For example:

• Part Area/Work Cell Area = Part to Work Cell Area Ratio
• Part/Work Cell X Arc Robot Quantity = Arc Density or Work Cell Productivity Ratio
• The Ratio of $ to Floor Space and # of Arcs = Value Ratio
• Integration Costs (1x per work cell): PLC +HMI + Power Drops + Tooling + Etc.

Example 1

A job shop or automotive company may consider the ArcWorld C-52 (AWC-52), which is a compact work cell for low to medium-volume fabrication that has two flat table stations (an AWC-52S has headstocks for turning parts). This cell delivers a powerful performance in a compact package, featuring:

• Reduced floor space
• One, six-axis Motoman robot
• Roll-up door
• Integrated welding package
• Max part size (millimeter) 760 x 700 capacity

Selecting a smaller work cell based on part size may appear to be the best use of floor space, but after considering the smaller part size in conjunction with the total footprint of the work cell, the overall area efficiency of this cell is only 12%.

In assessing the cell’s production capacity, the number of arc welding robots was evaluated as well. After calculating the part area to robot ratio and comparing it to the number of arcs, it was determined that the AWC-52 work cell productivity ratio was still 12% efficient due to the single robot.