Writing a Product Design Specification
Product Design and development involves a number of processes in order to increase the chances of success once in the market. To do this, the process of product design is initiated with the creation of a product design specification or PDS. The PDS documents all of the necessary requirements and constraints the new design must adhere to. It can also be said the PDS outlines what the market demands of the product and often involves detailed market research. Solutions or concept designs should be generated with reference to the PDS.
The number of sections or areas of specification can vary from one design team to another; however there are some recommended headings as detailed below:
- What does the product need to do?
- What speeds does it need to operate at?
- What loads will it experience?
- Can the performance required be realised at a reasonable, practical cost?
- Will making the performance specification more lenient help lower the cost?
Target production cost
- Estimate the realistic cost of making your product, including materials, manufacturing processes and down-time
- Analyse competing products currently on the market
- How many units are required to be produced?
This affects production costs and can even mean alternative manufacturing processes need to be considered
Product life span
- Estimate how long the product is to stay on the market
- Are there any customer demands?
- Focus groups or questionnaires are often used to find this information out and can mean greater success for the product
- Are there any similar products on the market?
- Are there patents that prevent or hinder your product from being developed?
- Ideas for your product can come directly from here and give an edge over other products
- How long do you intend the product to last?
- How often will it typically be used and at what rate will it operate?
- What type of environment will the product be subjected to?
- What is the ambient temperature, pressure and humidity?
- Is there dirt, dust or insects?
- Are there any corrosive fluids or chemicals?
- Is any vibration or noise expected?
- Wear and tear?
- What about storage and transit?
- Maximum allowable size of the product?
- What is the allowable weight range of the product?
- Heavy products require lifting points
- Is there any maintenance required? If so, how much is the customer expected to be able to carry out?
- Parts that need maintenance will need to be easily accessible
- Specify any special materials to be used, quoting any standards that must be adhered to?
- Specify material restrictions or those to avoid in the interest of safety i.e. toxic
- The product must be easy to operate, handle , adjusted, maintained and so on
- The height, posture and strength are amongst the variables of the target user that must be considered
- The appearance of a product is one of the most important aspects in the customer buying process and can often make all the difference when compared to a similar product
- The product may need to be compact, easy to use and look robust
- Specify the colour options and surface finish required
Quality and reliability
- Quantify using statistical data from similar products
- Will the product need any special or robust packaging solution taking into account transit?
- Which countries / regions of the world is your product intended to be released?
- Specify the appropriate standards and regulations
- Specify any planned tests that need to be carried out such as corrosion tests, accelerated life and fatigue testing
- How will the data be collected?
- How much will any tests cost?
- The product should be designed for safe operation
- Safe operating instructions should be mentioned clearly in any literature and/or on the product itself
- Any legal obligations must be observed
- Schedule enough time for the design phase of the product development process
- It is often costly to modify a design during or after production
As you can see, there are important details to specify and most refer to the functional aspects of the product. The form or appearance is considered but often after the functions, since ultimately the product should ‘do’ what it is designed to do. There is no point in having an aesthetically-pleasing product that fails to perform its functions. The PDS is an integral document to the whole of the design process.