How to Determine Cycle Time

When making decisions on assembly equipment purchases, one critical factor is whether or not the equipment will operate fast enough to meet volume requirements. While it’s important to know the estimated cycle time of the equipment itself, there are many other factors that can influence if a proposed assembly machine concept will allow manufacturers to meet volume requirements.

The first thing manufacturers need to know is what the required cycle time is based on the annual volume requirements. This is calculated based on the annual volume requirements, desired efficiency percentage, work days per year, shifts worked per day, and hours worked per shift using the following steps:

1. Take the annual volume requirement (EAV) and divide it by desired efficiency percentage (eff%) to factor in the efficiency.
2. Take this number and divide it by the number of work days per year (days/year) to give you the volume requirements per day.
3. Then, you take the daily volume requirement and divide it by the total number of hours worked in a day (hrs/day) to give you the number of parts per hour.
4. Finally, you take 3,600 (the number of seconds in an hour) and divide that by the number of parts per hour to get the cycle time required per part.

These steps can also be combined into the following formula, where the first three steps are combined into the bottom portion of the equation:

For example, if the annual volume is 400,000 with 240 working days, 8 hours per day, and the desired efficiency is 85%, the calculation would look like this:

1. 400,000 divided by .85 equals 470,588
2. 470,588 divided by 240 work days equals 1,961 parts per day
3. 1,961 divided by 1 shift per day, divided by 8 hours per shift equals 245 parts per hour
4. 3,600 divided by 245 equals a total cycle time of 14.7 seconds per part

Now that the required cycle time has been calculated, we can start to determine what equipment is required and what level of automation may be necessary. However, it isn’t as simple as looking at how fast the assembly equipment will operate. There are other factors to consider as well, such as:

• The hardness of the material being formed, as this may increase the equipment cycle time.
• The time it takes to load components and unload the completed assembly.
• If any other features are required that may take up time such as a clam-shell fixture or a slide package to move the part into forming location.

Once all these factors are taken into consideration, there is a clearer picture of what type of equipment is required. We start by looking at a standard piece of equipment, but if that is at or above the required cycle time, some level of automation may be required. This can be as simple as an A/B fixture slide to allow for load/unload and forming to happen at the same time, or as complex as a multi-station dial with part feeding and auto-unloading.

Orbitform’s Assembly Experts stand ready to discuss your volume requirements and can help you determine the appropriate level of automation based on cycle time, budget, technical experience, and more. Contact us today to discuss your application and ensure your assembly equipment meets your requirements.