An engineering drawing revision lands from the customer. The bore size changed. The planner emails it to the supervisor. The supervisor's WhatsApp mentions it to the CNC operator. But the CNC operator is mid-cycle on the first batch. He doesn't see the message till the batch is done.
Twenty parts with the wrong bore size. They cannot be used. They cannot even be reworked — the material cost, the machine time, the operator time, all wasted. You call the customer and negotiate who pays for the replacement batch. Even if the customer covers the material cost, your machine sat idle for a batch you didn't need, and your operator ran parts that didn't earn revenue.
Why rework kills margin
Rework is not a line item you can see. It is hidden inside lost efficiency. The machine was supposed to run Job 1142, but instead it ran a batch that became scrap, so now Job 1142 is delayed, so now the operator is working late, so now you have a small overtime bill. It is not one cost — it is five costs, each small, each looking like something else.
A typical custom manufacturer loses 3–7% of margin to rework and the cascade it creates. That is not rare. That is normal. And most shops cannot tell you where it went because it is not rework — it is inefficiency, overtime, delays, customer discounts for late delivery.
The communication gap is the root
A drawing change takes five paths to the floor. Email to the planner. Message to the supervisor. A note in the chat. A phone call at lunch. A verbal message passed between shifts. One of those paths is slow. One person doesn't see it. One shift change breaks the chain.
The CNC operator is the last to know because he is the person most affected. He gets the drawing change by rumor or by seeing a marked-up print, often when the batch is already starting. It is too late.
The fix is not to send more messages. It is to send the message to the person executing the job before they start executing it, with enough lead time to digest it.
What rework actually costs
A 30-piece batch that needs rework costs you the machine hour, the operator hour, and the material. That is 3–5k rupees in material and labor. But it also costs you a slot in the schedule — a machine that should have been running Job 1144 is now running a rework batch. Job 1144 is delayed. Now something else is delayed. A customer misses a deadline and takes a discount.
The original cost is 5k. The cascade cost is another 8–10k in lost efficiency, rework, delays, and discounts. You see a 5k charge on the job and you miss the 10k that bled out of other jobs.
Most shops are blind to it
You track job profitability, but you do not track why a job was less profitable than it should have been. You know Job 1142 made 18% margin instead of 22%, but you do not know it was because of three days of unplanned rework on a related job that ate a machine slot. That loss is invisible.
If you could see it, it would stun you. A 30-machine shop with 20% average margin is probably losing 3–4 margin points to preventable rework. That is 15–20% of your profit.
How to shrink it
- Every drawing change, material change, or sequence change lands on the operator's screen before the job starts
- Not in an email that requires reading, not in a message that requires scrolling back — on the job ticket itself
- The operator confirms they read it before the job begins
- The planner knows immediately if a change didn't get through, so they can call the floor
One manufacturing firm we worked with had a rework rate of 4.2%. After three weeks of using Wisemove to make sure every drawing change reached the floor before cutting started, the rework rate was 1.8%. That difference was 2.4 margin points. Over a year, that is profit that didn't bleed out.