Industrial Activity: Light Manufacturing

Every product follows a path from material to finished item. Waiting and carrying often take more time than working. In this module you draw that path and find the slowest step.

• Draw each step from material in to product out, using boxes for work and arrows for movement.
• Time each step with a clock on three different parts and use the average.
• Mark steps that add no value, such as waiting, carrying, searching for tools and rework.
• Name the slowest step, since the slowest step limits how many parts you can make in a day.
• A common mistake is to speed up a fast step, which only builds a pile of parts before the slow step.

Activity. Draw a flow map of your batch process with times for each step, and mark waiting and carrying steps.

Standard to meet. Time all steps, mark non-value steps and name the slowest step with its time.

No batch starts without a safety plan that a qualified supervisor has signed. Safety rules differ by place, so you check with your local authority. Habits such as protection and tidy work areas prevent most injuries.

• List every hazard in the batch, such as moving parts, sharp edges, dust, noise, heat, lifting and electricity.
• Write a control for each hazard, such as a guard, a lock-out step, ear protection or a lifting limit.
• Wear the protection the plan requires, tie back hair and loose clothing, and never wear jewellery near machines.
• Learn where the emergency stop, first-aid kit and exits are before you begin.
• Do not start work until a qualified supervisor has read and signed the plan, and check with your local authority for rules that apply.

Activity. Write a safety plan with hazards, controls and protection for your batch and obtain a supervisor's signature.

Standard to meet. Give each hazard a control, mark emergency points and sign and date the plan.

Everyone must make the same part the same way. A drawing shows size and tolerance, and a gauge or tool checks it. You learn to read a simple drawing and measure with care.

• Read the title, scale, units and each dimension on the drawing before you cut any material.
• Tolerance is the allowed difference from the target size, written as plus or minus a number.
• Choose the right tool for the tolerance, such as a steel rule for 1 mm and a calliper for 0.1 mm.
• Measure at the same point on every part and write the result in a table.
• Mark parts outside tolerance and set them aside, never mix them with good parts.

Activity. Measure five parts against a drawing and record each size, the allowed range and pass or fail.

Standard to meet. Put all five measurements in a table with the range, judge each pass or fail correctly and set failed parts aside.

A good plan lists materials, time and people before you start. It also includes an allowance for waste. You will build a bill of materials and a time plan for 50 parts.

• List every material with quantity per part and for the whole batch, with units such as kilograms or metres.
• Add a scrap allowance, usually 5 to 10 percent, because cutting and testing always lose some material.
• Time each step per part and multiply by the batch size to find total hours.
• Check stock and order missing material, noting the lead time so that you do not stop mid-batch.
• Write who does each step and what tools they need.

Activity. Write a batch plan with a bill of materials, a scrap allowance, times per step and a list of tools and people.

Standard to meet. Include scrap in quantities, calculate total time correctly and check stock.

Running a batch is where the plan meets reality. You log time and defects as you go and stop when the pattern changes. Tidy work keeps both quality and safety high.

• Log the start and end time for each step and the number of parts finished every hour.
• Check the first part fully before running the rest, and check every fifth part afterwards.
• Write each defect with its type and the time it happened.
• Stop and investigate if two defects of the same type happen close together, instead of continuing and wasting material.
• Clean the area at the end of every shift and return tools to their place.

Activity. Run the batch with a time log, a defect log and a record of each stop and what you changed.

Standard to meet. Log every step, count defects by type and give each stop a cause and action.

Quality work finds causes instead of blame. You count defects by type, find the biggest group and trace it to the root. Then you fix the cause at its source.

• Count defects by type in a table and calculate each type as a percentage of all defects.
• Sort the table from largest to smallest and work on the largest first.
• Ask why five times: keep asking why the problem happened until you reach a cause you can change.
• Fix the cause, for example replace a tool or change a method, rather than only fixing the part.
• Check again after the fix and record whether the defect count fell.

Activity. Chart the defects by type, find the root cause of the biggest group and write the corrective action.

Standard to meet. Show counts and percentages on the chart, reach the root cause by repeated why questions and give an action an owner.

Cost per part decides your price and your profit. It includes material, labour, energy and waste. You count only good parts, because bad parts add cost without value.

• List material cost with the scrap included, labour at a fair hourly rate, energy and tool wear.
• Add up the total batch cost and divide it by the number of good parts, not by the number started.
• Compare your cost per part with a price quote for the same item to see if you are competitive.
• Find which line is biggest and think about how to reduce it.
• Put a currency on every line and ask your mentor to check the sheet.

Activity. Build a cost sheet for the batch and calculate cost per good part.

Standard to meet. Give all lines a currency, get the total correct, divide using good parts and have the mentor check it.

Improvement means one small change that you measure. You choose the slowest or most wasteful step, trial a change and compare the numbers. Changing one thing at a time shows what really worked.

• Pick the step that limits output or causes the most defects, using your flow map and defect chart.
• Write the change you will trial, the number you expect and how you will measure it.
• Change one thing only, such as a jig, a tool position or a work order, and run a small test.
• Measure the same number before and after, and calculate the change in percent.
• If it works, write it into the standard method, and if not, record why and try another idea.

Activity. Present one improvement with the problem, the change, and numbers before and after.

Standard to meet. Measure the numbers before and after the same way, calculate the percent change correctly and change only one thing.