Planning Documents
An engineering drawing or blueprint may be thought of as a map that defines the destination. This destination is the end product. The roads available to get to this destination may be numerous. We do not start the trip without first determining what the destination is and how we are going to get there.
Planning sheets resemble the required path to the destination. They are written descriptions of how to get there (to the end product). The following are descriptions of sample planning documents.
The Engineering Drawing or Blueprint
The information given on the engineering drawing or blueprint will include the material, overall shape and the dimensions for part features (Figure 1-7). The geometry determines the type of machine (mill or lathe) to be used to produce the part. By studying the engineering drawing or blueprint, material and operations (drilling, milling, boring, etc.) can be identified. The tools and work holding method can also be determined. Occasionally, the geometry will require multiple machines to manufacture the part, and thus additional operations will be necessary.
Figure 1-7 Machined Part Engineering Drawing
Chart 1-1Process Planning Operation Sheet
| Date | Prepared By | ||
| Part Name | Part Number | ||
| Quantity | Sheet ___of ___ | ||
| Material | |||
| Raw Stock Size | |||
| Operation Number | Machine Used | Description of Operation | Time |
Operation Sheet
The purpose of this planning document is to identify the correct order for operations to be performed and the machine to be used. For example, suppose you are required to produce the part shown in Figure 1-7. You would first saw cut the rough stock into blanks and then turn the part on a lathe to create the five-inch diameter and rough turn the diameter for the hexagon. Next, you would use a milling machine to cut the hexagon and drill the bolt-hole circle. Before any inspecting the part for accuracy, you would deburr the part.
The operation sheet is particularly useful when many identical parts are machined (production run). The operation sheet is similar to directions or a how-to approach. The process needed to manufacture the finished part has been decided in advance and is documented for future use.
When small batches of parts are to be made, there may not be an operation sheet. It is the machinist’s responsibility to study the engineering drawing or blueprint and decide the necessary steps to machine the part. The operation sheet can aid in this decision making process (Chart 1-1).
With CNC machining, multiple part geometry features can be performed in one setup. In some cases, when using a CNC mill turn center, a part might be machined to its completed status without ever using another machine. This is very efficient and another advantage of the use of CNC equipment.
To complete an operation sheet, study the engineering drawing or blueprint; then decide on the steps necessary to machine the part. Document the machining process and refine any problems the process has. Then list the operations in the correct sequence in which they will be performed.
The top section of the operation sheet is for reference information and includes:
• The date the document is prepared or revised
• The name of the person preparing it
• The part name and the part number (from the engineering drawing or blueprint)
• The quantity of parts to be manufactured
Because some parts require a large number of operations, it is possible that more
