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Special characteristics matrix template

A special characteristics matrix is a table that lists every special characteristic of a part and follows each one through the documents it has to appear in: the drawing, the process flow, the PFMEA, the control plan, the gauge and its measurement study, and the capability result. This template has a one-page matrix and an Excel file that names the first thing missing on each row, and counts the rows with a gap, so nothing special is left uncontrolled.

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Page 1 of the special characteristics matrixHeader fields for part, customer, drawing and level, above a table with 14 numbered rows and columns from characteristic and class to control plan line, gauge study, target, latest capability and gap.
Characteristic and symbolProduct or processWhere definedProcess stepPFMEA and control plan linesGauge and measurement studyTarget and latest capabilityFirst gap on each row
Filled-in Special characteristics matrix template: ten special characteristics, four gaps
The same sheet filled in with the worked example (page 3 of the PDF, illustrative numbers). Open full size (opens the picture in a new tab)

When to use it

When to use a special characteristics matrix

  • During APQP, once the customer's drawing and requirements are in, to list what has to be controlled and prove it is.
  • Before a PPAP submission, to find the gaps while there is still time to close them.
  • After a drawing, PFMEA or control plan change, to check the characteristic is still on every document.
  • At each program meeting, as a short list of open gaps with owners.
  • Not as a replacement for the control plan. The matrix points to it and shows where it is silent.

How to fill it in

  1. 1

    List the characteristics from the customer first

    Take them from the customer's drawing and requirements, then add the ones your own PFMEA marks as special. One row each.
  2. 2

    Use the customer's symbol

    Customers use different symbols and classes, and the customer's drawing legend says what each one means. Put the symbol in the Class column and keep any internal class in a separate column.
  3. 3

    Mark product or process

    A product characteristic is a feature of the part you can measure. A process characteristic is a setting or condition that controls one, such as weld current. Give each its own row and point process rows back to the product feature they protect.
  4. 4

    Fill in where each one lives

    Where it is defined on the drawing or spec, the process step, the PFMEA line, the control plan line, the control method and the gauge or monitor.
  5. 5

    Record the gauge study and the capability

    For product characteristics, say whether the gauge has a measurement system study, then enter the target Ppk or Cpk and the latest result.
  6. 6

    Read the Gap column and close the gaps

    The Excel file names the first thing missing on each row. Put each gap on the program's open issues list with an owner and a date, and review it until the count is 0.

The chain

What to check at each link, and the gap that shows when it is missing

The Gap column reads the links in this order and stops at the first one that is missing.

  • Drawing or spec

    What to find
    The characteristic is marked, with the customer's symbol, at the change level in use
    Gap shown if missing
    No drawing reference
  • PFMEA

    What to find
    A line with the same symbol and the prevention and detection controls
    Gap shown if missing
    Not in the PFMEA
  • Control plan

    What to find
    A line with the method, sample size, frequency and reaction plan
    Gap shown if missing
    Not in the control plan
  • Gauge study

    What to find
    The gauge is named and has a measurement system study
    Gap shown if missing
    Gauge study not done
  • Capability

    What to find
    For a product characteristic, a Ppk or Cpk from a run that meets the target
    Gap shown if missing
    No capability result, or Capability below target

A filled-in example

Illustrative, not a benchmark

An example (illustrative): ten special characteristics of a seat frame bracket, SB-4410, for Example Motors (made up). CC and SC stand in for a customer's symbols. All references and numbers are invented.

  • Ten characteristics: 6 are Covered and 4 have a gap. Seven are product characteristics and three are process characteristics.
  • Row 1, hole A position (CC): a Ppk of 1.52 against a target of 1.67, so the gap is Capability below target. It is the same number the made-up warrant stops at.
  • Row 5, burr height on edge E (SC): it is on the PFMEA but there is no control plan line, so the gap is Not in the control plan.
  • Row 6, hole B diameter (SC): it has a control plan line and a Ppk of 1.40, but its pin gauge has no measurement system study, so the gap is Gauge study not done.
  • Row 10, flatness of base (SC): it is on the control plan with a Ppk of 1.45 but missing from the PFMEA, so the gap is Not in the PFMEA.
  • The three process characteristics (weld current, press tonnage and oven temperature) are Covered because each is on the PFMEA and the control plan and has a monitor marked as checked. This sheet asks for a capability result on product rows only.

Four rows, four different missing links, each with a clear next step. Nobody has to read three documents side by side to find them.

Common mistakes

  • Listing only what is on the drawing

    Your own PFMEA may mark characteristics the customer did not. Add them, with your own class in a separate column.

  • A symbol that changes between documents

    If the drawing says one thing and the control plan another, the floor follows the control plan. Use the same symbol on every document.

  • Capability without a gauge study

    A Ppk built on a gauge nobody has studied hides gauge error inside the process. Check the gauge first.

  • Leaving process characteristics out

    Many product features are held by a process setting. If only the product row is listed, the setting that protects it can drift unwatched.

  • Not updating after a change

    A matrix that is out of date is worse than none, because people trust it. Update it with every change to the drawing, PFMEA or control plan.

Download the template

Free to use: print it, copy it and edit it for your team. Enter your name and work email once to download.

Run this template in LeanSuite

In LeanSuite quality checks run as digital checklists with number limits, an out-of-spec answer can raise a tag or start a CAPA automatically, and KPI Builder tracks quality KPIs against targets.

See it in a 45-minute demo

FAQ

Special characteristics matrix template: common questions

  1. A feature of a product or a process that your customer or you have decided needs extra control, usually because it affects safety, regulatory compliance, fit or function. Customers use different symbols and classes for them, so use the ones on your customer's drawing.

  2. Your customer's. They differ between customers and the customer's legend says what each means. This sheet has a Class column for the symbol and nothing in it is a default.

  3. This sheet asks for one only on product characteristics. Process rows are Covered when they pass the drawing, PFMEA, control plan and gauge or monitor links. Your customer may ask for a capability result on process rows too.

  4. It reads each link in order and shows the first one missing: drawing reference, PFMEA, control plan, gauge study, then capability for a product row. If every link is present and the latest capability meets the target, the row is Covered.

  5. No. The control plan says how each characteristic is controlled on the floor. The matrix shows whether every special characteristic is on the control plan, the PFMEA and the drawing, and whether it has been proved.

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