Calculating Line Speed

Question:

When designing a paint line system, how would I calculate the “feet per minute” using a monorail system? We are looking at a three stage pre-treatment system, dry-off oven, wet paint booth, powder booth and curing oven. Our product is 28 ft long × 8 ft high × 12 inches wide. T.Z.

Answer:

The answer to the question you raise can be both complex and simple. It is complex because line speed in feet per minute depends on a number of parameters. Some of these parameters are as follows: length of the various subsystems in the finishing line; required dwell time in each of the subsystems; and size of the product. These parameters are further complicated by the production schedule.

Since you are designing the finishing system, there are some important issues to remember. You must calculate the length of each of the subsystems. The lengths of these subsystems will depend on the total length of the finishing system and on the space available for the finishing system. These lengths will also depend on the dwell times in each subsystem and on the product dimensions. The most important dimension is the length of the product. That would be the dimension of the product, as it is hung, parallel to the monorail conveyor. The product length will also determine the radius of any curves in the conveyor line. Don’t forget about product overhang around curves. As you can see, the complex answer is beyond the scope of Painting Clinic.

However, the simple answer can be shown by the following typical line speed calculation: If the cleaning stage cabinet is 3 ft long and the cleaning stage requires a 3 min dwell time, the line speed would be 3 ft divided by 3 min which equals 1 ft/min. On the other hand, if the cleaning stage cabinet is 15 ft long and the cleaning stage still requires a 3 min dwell time, the line speed would be 15 ft divided by 3 min, which equals 5 ft/min.