In our book, Secrets of Buying Packaging Machinery John Henry and I devote an entire chapter to machinery specifications. Well written specifications are a must in any project for several reasons.
- The buyer needs to write a good specification to clarify their own thinking about what they want to buy. If they buyer can’t put it down on paper, they may not have thought it through completely.
- If, as it usually the case, multiple people in the company are involved, the specification clarifies exactly what is being purchased. A written document makes it easier for others to verify that it meets their needs. The specification becomes, in a sense, a contract among all involved internally. Ideally, everyone should sign off (literally) that they are in agreement with the specification.
- Packaging machinery can be somewhat complex and there is plenty of room for the machine builder to misunderstand what the buyer wants. Conversely, there is plenty of room for the buyer to misunderstand what the builder has agreed to provide.
Well written specifications avoid all that.
There are two schools of thought on how to write specifications. One school says that they should be complete and detailed, almost down to the last nut and bolt. This does assure the buyer that they will get exactly what they want but what they want may not be what they really need.
The other school says that specifications should be written functionally. Instead of telling the machine builder that you want a 4 head filler with 2″ diameter pistons and 1/2″ diameter nozzles, tell them what the filler should do. “Fill a waterlike product into a 6oz bottle at a speed of 100bpm.” It is then up to the builder to propose a machine that will do this.
In most cases, there will be some combination of detail and functionality. The buyer provides the functional requirements plus such details as may be required. e.g. “PLC shall be Allen-Bradley Model _______”.
The exact format of the specification is nowhere near as important as the fact that a specification exists. Good specifications are the only way to assure that you get what you want.
