Testing and Evaluation Methods
To keep focused on the design brief it is helpful to check that ideas are relevant and appealing at each stage of the design process. This can be done in a number of different ways to help suggest improvements to the product design.
- Testing design ideas against the design criteria listed in the design specification
- Ideas showed to the intended users to collect feedback comments
- Expert opinions sought to test the appropriateness of proposed materials, techniques and processes
- Samples and prototypes tested and trialled
- Comparison of own product design to a similar existing product
The testing is often carried out using questionnaires or interview questions that seek views about the performance, price and appeal of an idea or prototype.
Testing Design Ideas
Market surveys can be carried out to discover what consumers prefer and what type of new product might interest them. Special market research companies may be commissioned to collect the data, or a company might invite a panel of shoppers to give their opinions.
Experts will have excellent advice to give to designers about design ideas, methods of making and proposed use of fabrics and components.
Testing the Product Prototype
Once a prototype has been made, designers need to check that their product:
- Is fit for purpose
- Is it the right price level
- Has appeal
- Includes appropriate materials and techniques
- Has a low impact on the environment
- Meets maintenance requirements
- Is easy to manufacture
The view of intended users can be collected by asking a sample of the target market to try out the product and record their opinions on how well it performed. A questionnaire could be used, an interview held, photographs taken or observations made in order to collect data.
Many companies are keen to get feedback from customers to check on the success of an idea for a new product and to help with further developments in their range of products.
It is useful to test the prototype against a similar existing product to see how the new product would compete with others on the market. The new product should be an improved or updated version with a unique appeal to the target market. Analysis of results form product comparison will highlight the differences between what is already selling and what might be sold in the future.
A very wide range of textile machinery is used to process fibres, spin yarn, construct fabric using knit, weave and bonding techniques, print, dye and finish it, and then make textile products from the fabric. Machinery speeds up each stage of manufacture, and make some processes automatic. As long as the operators are well trained, machines can improve safety in the workplace, be more cost-effective and make quality consistent. Machine to transport materials, monitor, and inspect production and package finished products assist the workforce and speed production. computerised machines have been introduced at the most stage of production to simplify the route from design to manufacture and improve systems and control.
Stitching by Machine
There are many different types of sewing machines; some perform very specialist tasks such as making buttonholes, overlocking fabrics edges or embroidered motifs.
Generally, a basic sewing machine can be used to join fabric pieces together and to decorate them with a small range of embroidery stitches. To operate the machine skilfully, training is essential and practice is required.
Neat and accurate work is produced within the right type of needle is used and machine settings are appropriate for the type of fabric stitched. For example, a ball-point needle and stretch stitch is required to join a knitted fabric, to ensure that the fabric is not damaged while stitching and that the seam made is as stretchy as the knitted fabric.
Computerised embroidery machines are used to interpret digitized artwork so that original designs can be scanned, outlined and filled with decorative stitching and then reproduced on to the fabric as embroidery. The machine can also embroider from a design menu to stitch patterns, panels, motifs and to personalise products with written script and numbers.
The operator prepares the fabric to be embroidered, by ironing light interfacing onto the back of the fabric to stabilise it. The fabric is held in a frame to present a flat surface for stitching. A range of different threads can be selected to clour the embroidery.
There are three main types of production systems:
When planning which production system to use, a manufacturer will need to consider the product type know how many products are to be made and the timing of delivery dates. Choice of the system will affect the way fabrics and components are ordered and what sort of training the workforce will need. Large-scale production reduces the cost of manufacturing each product. Factory floor layout of workstation and production lines will be determined by the type of system in place.
- One-OffIndividual items are made once, by hand or by highly skilled machine operators. One-off products are exclusive and made by a craftsperson or designer-maker to meet an individual client’s requirements. This production system is also known as bespoke, made-to-measure, custom-made or jobbing production. Haute couture garments are made in this way.
- BatchA team of workers will work to complete an agreed number of identical products. Production costs are lower than for one-off production.
- MassLarge number of identical products are manufactured over a long period of time. This is also known as volume production and usually involves a production line to make items that are in continual demand such as white T-shirts. It is the cheapest system because materials can be bought in bulk and automated machinery and computer-aided manufacturing are used as much as possible to cut labour costs.
In mass production, each machine operator works on a section of the product before passing it along to the next machinist to carry out the next stage of making. The workers much ensure that they work speedily to agreed standards to that the whole production line runs smoothly and is very cost effective. For cheap, simple products the machinery often runs continuously with machine operators working on shifts.
It may before efficient to join and attach small parts of a product together in an operation separate from the main production line. For example, a whole shirt collar is made before attaching it to the top of the shirt. Some production systems may have several subassemblies, some of which may be done in another workplace.
Just-In-Time Stock Control (JIT)
This is a cost-effective method of ordering fabrics, components and sub-assemblies to arrive just before they are needed. Stock storage time is reduced but any mistakes and delays in deliveries will hold production up.
Hand Tools and Equipment
It is important to select the correct tools and equipment, to know how to use safely and effectively and to maintain them in a clean, undamaged condition. This will allow the person using the tools and equipment to produce accurate work, resulting in a well-made product.
The following tools and equipment are the basic kit required for designing, colouring and embellishing fabrics:
- A range of pencils, pens, scissors, and rulers
- Colouring equipment to dye fabric, such as fabric crayons, fabric pens, fabric paint, print paste, powder or liquid dye
- Protective apron and gloves to prevent dye from staining fingers and clothing
- Brushes, spray diffusers, screens and squeegees to apply the dye or fabric-print paste
- A range of needles for hand stitching, decorative stitching and beading work (beading is done with long, very fine needles so that even the smallest group of beads can be threaded along the needle, whereas stitching through open-weave fabric with a woollen thread is done more easily using a blunt-ended needle with a large eye)
- A metal or wooden hoop for use in embroidery to keep the fabric flat when stitching; this improves accuracy and makes it safe when using a needle
- A flexible measuring tape is used to measure curved surfaces accurately. A pattern master is used when making paper patterns to help draw curved lines and add seam allowance
- Tailor’s chalk or soft pencils are used to transfer marking on to the fabric
- Craft knives allow for more detailed and accurate results than scissors when cutting stencils for spray and print techniques. Use of mats when cutting with a knife prevents leaving cutting marks on the table surface
- Scissors are made in a variety of sizes according to their purpose. Sort, sharp scissors are useful for detailed cutting work when snipping threads during embroidery or clipping curves when pressing seams, whereas longer, thicker blades will cut across fabric quickly and more easily. Pinking shears help with edge finishing to the neater fabric. Left-handed people need scissors with blades aligned for them.
- Seam rippers will make the job of unpicking seams easier and quicker. Ther will be less chance of cutting the fabric instead of the stitching thread when using this hand tool.
- Irons or heating presses are used to flatten fabric, press seam open, heat set fabric or heat transfer print designs on to fabric. Ironing or pressing is more effective if steam is also applied.
- Heated pots are used to melt the wax used in batik. Metal training tools, which looks like a small metal down on a long handle, heat up to keep the wax warm and fluid and are used to transfer the was on to the fabric. The pot has a lid, a short cord and has a thermostatic control to ensure safety. This is important because if the wax overheats it could ignite; it spills it could burn the person using the hot wax.
- A hat makes use a head-shaped block to enable them to mould felt to the correct shape
- Fashion designers use a manikin to give correct figure measurements and body shape to build patterns from and to check garments for fit
- Pins are used to holding pieces in position on the manikin, and to temporarily join pieces, prior to tacking or stitching.