WJEC Vocational Award Engineering Level 1/2

Chapter 9 Managing and Evaluating Production Using the correct settings and speeds for the machines will ensure: • a good-quality finish • longer working life of the part/machine (no breaking) • safer operation (user not being hurt). By not using the correct data you could: • destroy your work (have to start again) • break parts or all of the machine • injure yourself or others. Following is an example of a data chart for a centre lathe. It contains useful information such as what RPM is needed when using different sizes of materials and different materials. Other useful information on RPM when performing specialist operations such as parting and knurling is shown in the Top tip on the right. GUIDELINE RPM FOR CENTRE LATHE Material diameter Material Inches Millimetres Aluminium Brass Mild steel Stainless steel ½ 12.5 1,400 1,200 1,000 600 1 25.5 700 600 500 300 1½ 38 500 400 300 200 2 50.5 350 300 250 150 2½ 63.5 280 250 220 120 3 76 225 190 160 100 Gantt charts Another big resource for many Engineers, whether working for a company or even trying to complete a prototype in school or college, is TIME. Time (along with cost) is one of the main constraints Engineers have when starting projects. Being able to organise time effectively is of great benefit when trying to manage projects. Having the ability to organise time effectively for projects means time is not wasted, money is saved and deadlines will be met. Gantt charts (invented by Henry Gantt 1861–1919) are widely used by Engineers and in industry to organise time effectively. ‘Time’, when producing a job sheet, has already been discussed. However, having a chart that organises time, which can be scanned and understood quickly, is a very effective way of managing time. Following is an example of a Gantt chart. This chart has been made for the engineering drawing example in this chapter. For this example you are concentrating on the ‘SHADE’ part only. Part: SHADE Process Total time 1 hour (5-minute segments) Marking-out Cutting Centre punch Drill Tap a thread Knurling and parting operations should only be run at 100RPM maximum. Top tip Constraint: limitation. Key term The process only took 35 minutes to complete so the Gannt chart shows there is more time available for you to start other processes. 91