Time and Motion Studies

In addition to manufacturing, some plastic injection molders also provide assembly services. While there are many different types of product assemblies, there are some basic approaches towards determining what the process will entail. One of those approaches is referred to as a time and motion study.

For our purposes here, a time and motion study is a technique used to analyze both the duration each step in a manufacturing process will take coupled with the mechanical and manual labor involved to complete each task. By describing and studying an entire assembly procedure and each incremental step within it, a company is able to design, map, plan, budget, schedule, and standardize its processes effectively. Additionally, the more thorough the study is, the more accurately the quoting of the assembly services should be. Further, once an assembly process is established, periodic analyses can identify areas of improvement, which may include time efficiencies, the elimination of wasted motion, automating certain tasks, and an increase in the overall effectiveness of the system.

When conducting a time and motion study in the plastic injection molding context, the same general methodology is taken, while factoring in certain considerations unique to the industry. Regardless of the type of assembly required, one of the first steps in the analysis probably will include a determination of whether the assembly can be performed at some point during the production process and, if so, at what stage and location within the facilities the work can be conducted in the most efficient and effective manner.

Next, the supplier might work on the sequencing of the manufacturing and assembly processes. This calculation can be fairly simple, or it might require more complexity. For example, if the assembly a molder is performing only includes combining two different parts they are producing, the review might include which part to manufacture first; how to stage finished parts by the molding machine producing the second parts; what the method of affixing the two parts together entails (e.g., gluing); what equipment, tools and fixtures are required; what the estimated molding cycle time for the second part will be; any cooling or curing time needed for the either part; any necessary surface prep work; what movements will be involved in the actual bonding; any finishing work, labeling or cleaning required; what inspections are specified; and how to package the final assembly. And, that’s just a simple process! A more complex assembly procedure can involve multiple components, numerous steps, and the need for outside vendors.

Two obvious benefits to having your molder perform some or all of your product’s assembly is that it often is faster and cheaper than sending the molded parts, along with other items, to an outside assembly services vendor. Having parts and components combined by molding machine operators, who might be handling the parts as they are produced anyway, can eliminate unnecessary steps, such as additional packaging and shipping. This usually translates into lower costs and shorter lead times.

Product assembly can be a complex procedure involving multiple items, equipment and processes. As such, performing a thorough time and motion study at the beginning of a program launch can provide valuable perspective and expectations, in addition to discovering cost savings and lead time reductions. Accordingly, any accurate estimating of assembly services should employ this practice.

If you have parts being manufactured by a plastic injection molding supplier, be sure to inquire about any assembly services they might offer and how they arrive at their figures. You might be pleasantly surprised that the review of time and motion often translates into less time and money.

If you would like more information, please do not hesitate to contact us. We’re here to help.


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