Process control
Within tolerance is a result. In control is a process
A certificate says a quality system exists. It does not say what happens when the third shift drifts, or whether a problem got solved or merely sorted.
These methods being deployed come from a Deming-track programme covering TQM, Six Sigma Green Belt, design of experiments and reliability, assessed on projects run inside the business rather than by examination alone.
During the run
Drift shows as a trend before it shows as a reject
A chart that only moves when a part fails was never worth keeping. The point is to see the process leaning while there is still time to nudge it back.
SPC and control charts
Variable and attribute charts on the characteristics that decide the part, so a trend is acted on rather than a rejection investigated.
Process capability
Cp and Cpk to show the process sits inside the tolerance with room, rather than passing because inspection caught the ones that did not.
Daily work management
KPIs reviewed against standard every day, with the abnormality response agreed in advance so nothing waits for a monthly meeting.
SDCA before PDCA
Standardise, do, check, act. An improvement only counts once the new level has become the standard rather than a good month.
Before the quote
The drawing is read before it is priced
A drawing arrives as a statement of intent, and it is treated as one. Reading it properly is the cheapest control available, because everything downstream inherits whatever was misunderstood here.
- Read for completeness first
- Drawings are checked for missing dimensions, absent datums, undefined finishes and tolerances that no stated process would hold, and the question is asked before a price is given. A query raised at quotation costs a phone call. The same query raised at first article costs a batch.
- The revision is confirmed, not assumed
- The revision being worked to is verified as current before material is cut, rather than trusting whichever copy happens to be on file. A superseded drawing produces parts that are correct against the wrong document, which is the most expensive kind of correct.
- Engineering changes are tracked to the part
- Where a change is issued against a part already running, it is recorded against that part, the control plan is revisited, and work in progress is reconciled to the revision it was made to.
- Disagreement is escalated, not settled locally
- Where a drawing and what the shop floor is seeing do not agree, the conflict goes back to the customer’s engineering contact for a written answer. A fit agreed verbally on the floor tends to be agreed differently on the next shift.
- Files are kept as they were sent
- Drawings, models and revisions are retained under the customer’s own numbering, so a request years later can be answered against the same document rather than a redrawn approximation.
None of this is glamorous, and it is much of the reason first articles pass. A shop that reads drawings carefully asks more questions at quotation stage, which can read as slowness. It is usually the opposite.
Before the cut
Most quality is decided before a machine starts
By the time a tool touches metal the outcome is largely fixed. What is left is whether anyone noticed in time.
- Process flow diagram
- Every operation from raw material to despatch, in sequence, so handling, storage and inspection points are visible rather than assumed.
- PFMEA
- Failure modes ranked on severity, occurrence and detection. What can go wrong, how likely it is, and whether we would catch it before you do.
- Control plan
- Per characteristic: what is measured, with what, how often, by whom, and what happens the moment it drifts.
- MSA and gauge R&R
- The gauge is proved before the process is judged. A measurement system that cannot resolve the tolerance will condemn good parts and pass bad ones, and it will do both quietly.
- Workstation standards
- The method written down at the machine, with operator skill built against it, so the process does not live in one person’s head.
- Error proofing
- Poka-yoke and fixture design, so the wrong orientation or the missed operation becomes physically difficult rather than merely discouraged.
When something goes wrong
The method is chosen to fit the problem
Reaching for the same tool every time is how a shop ends up solving the easy half of a problem repeatedly.
| The problem in front of you | What gets used | What comes back |
|---|---|---|
| A defect with a visible pattern | QC Story with the seven QC tools: Pareto, cause and effect, stratification, scatter, histogram, check sheet, control chart | Containment inside hours, then a root cause carrying evidence rather than an opinion |
| Something nobody can pin down | Six Sigma Green Belt: business case, team charter, sampling, hypothesis testing, control methodology | A cause supported statistically, and a control that keeps it there |
| Several factors interacting | Design of experiments: full and fractional factorial | Which factors matter, how they interact, and settings that are robust rather than lucky |
| A clear difference between good and bad parts | Shainin methods: multi-vari, component search, paired comparison, product and process search | The dominant cause isolated by comparison, without theorising first |
| A failure that keeps coming back from the field | Reliability engineering: product life cycle and B10 life | Where in its life the part gives up, and what to change so it does not |
Underneath all of it
The habits that make the rest possible
- Lean
- Value stream mapping, flow and pull, SMED on changeover, line balancing, visual management. A changeover cut from hours to minutes is what makes your smaller batch affordable.
- TPM
- The sixteen losses, OEE and operator-led maintenance, so machine condition stops being a hidden source of variation.
- QC circles
- Operator-led improvement, with human error treated as a design problem rather than a discipline problem.
- Policy deployment
- Objectives cascaded and tied to daily management, so a target reaches the machine instead of the noticeboard.
- Audit practice
- ISO and IATF auditing skills held in house, which turns an audit into a review rather than an event.
- Industry 4.0
- Machine and process data read as variation happens, not in next month’s report.
Bring it into the enquiry
Say what your quality system needs when you send the drawing: PPAP or ISIR documentation, a control plan, capability studies on nominated characteristics, gauge R&R against a gauge you supply. It gets priced in from the start, which costs both of us less than finding out at first article.
Send the drawing
A straight answer inside a working day
A 2D or 3D file, the quantity and the date you need it. You will get a considered reply within one working day, including the reply that we are not the right shop for the part, which is worth knowing early. A mutual NDA goes out first if you would rather.