Machining Time Calculator | Shop Cycle Planner

Machining time are a quantity that requires precise calculation. The time required for machining include many different factor beyond the length of the cut that must be made in the workpiece. Factors like travel time, tool change time, and time for tasks that occur before the spindle begin to move the tool must be accounted for.

Failure to account for these factor will lead to incorrect estimate for the total time required to perform the task. Each of these factor must be individually considered when calculating the total time required to complete a job. Factors like the length of approach and overtravel must be considered for some operations, but not other.

How to Calculate Machining Time

Factors like the number of passes that is required for a job must be considered, as well as factors like the length of rapid moves between features (which might be ignored in some cases). Each of these distance will be multiplied by the feed rate to determine the time for each of these tasks. However, the feed rate that is entered into the calculation may not be the rate at which the machine will actualy travel; factors like corners, chip load, and overrides may alter the actual feed rate of the machine.

Thus, the calculator can handle the arithmetic of the calculation once the distances and rates are entered, but the calculator will help to avoid the mistake of rounding these number to convenient values. The type of operation will affect the machining time for each job, as well as how it is calculated. For operations like facing, the factor that is applied to the length of the task is close to one.

For operations like slotting, the factor is increased due to the deeper engagement of the cutting tool with the workpiece. For operations like drilling, the factor is increased due to the number of pecks that the tool make in the workpiece before retracting the tool. Finally, tapping introduces time into the operation; tapping requires the cutting tool to move in the opposite direction of the rotation of the tool.

Each of these operations has different factor that must be accounted for due to the differences in the physics of each of these operations. These tables can help provide those factor, as well as to explain why some job may take longer then others. The batch size for a job will affect how machining time is calculated for that job.

For instance, setup time is a cost that is applied to the job only once, but can be divided among each of the part that are produced. Similarly, tool change time behaves in the same way. For a batch size of one, tool changes and the initial setup will contribute to the total time for that job.

However, for batches of fifty or more part, those initial cost will be relatively small when compared to the total time for each individual part. Finally, an adjustment factor acknowledges that not all job are performed with the same efficiency as theoretically possible. For instance, a five or ten percent factor can be used to account for normal chip clearing; a twenty percent factor may be used for the initial production of a job (as an operator must watch the operator to make sure that the tooling is set up correct).

Finally, the materials from which the parts are made will impact the machining time for those part. For instance, aluminum allows for higher feed rate due to the fact that aluminum pieces allow for the easy clearing of chips from the workpiece. However, stainless steel can lead to work hardening of the material if the feeds and rates isnt carefully managed.

Finally, titanium tends to create heat during cutting operation, which may lead to a shortening of the life of the tooling if the operations are not carefully managed. The ranges for feed rate in these tables are provided to ensure that the entered feed rate is within realistic parameters for that material; using a feed rate within the normal range for a material will ensure that the calculated time to complete the machining task is believable. Rapid movement of the cutting tool is another component of the total machining time.

However, rapid movement only occurs when the tool is not cutting the workpiece. In addition, the rate at which the cutting tool can rapidly move to a new position is typically less than the maximum rate for the machine. To account for this, the operator should enter the rapid movement rate as a conservative guess of the rapid movement rate for the tool.

Related to the tool movement is the time that it takes to change a tool. For instance, modern milling machine typically perform tool changes in under a minute; however, the same operation on an older machine may take much longer due to the need for manual changes to the tooling. Perhaps the most important number that the machine and operation time calculator can calculate is the split between the cutting time and all other types of time for that machining operation.

If the cutting time is less than one-third of the total time for the job, then the job is actually spending more time moving, setting up, and changing tools than it is cutting the material. In this situation, there are a variety of option for improvement: one could use a better workholding strategy to reduce setup times, for instance. Or, another could reduce the number of tool changes required for the job.

Finally, another option is to simply decide that short runs are not efficient by their nature, and to quote the job based on that fact. Thus, calculating these value allows for a job to be better defended when quoted at a shop.