NADCAP AC7101-5 Rev C

 AC 7101/5 REV. C

 AUDIT  A UDIT CRITERIA

Issued 1993-05 Revised 2011-05

161Thorn Hill Road Warrendale, PA 15086-7527

Superseding AC7101/5 Rev. B

TO BE USED ON AUDITS CONDUCTED ON OR AFTER A UGUST 28, 2011 Nadcap  AUDIT CRITERIA FOR MATERIALS TESTING LABORATORIES – HARDNESS TESTING (MACRO)

1.0

SCOPE This checklist supplements PRI AC7101/1. This checklist applies to suppliers seeking Nadcap accreditation for Materials Testing Laboratories – Hardness Testing (Macro).

2.0

GENERAL INFORMATION

2.1

Laboratory

2.2

Laboratory Contact

2.3

Auditor

2.4

Initial Accreditation

Re-accreditation

Follow-up

NOTE:

The Bold sections in this document represent the interpretations for each section of this checklist. Items noted with a single asterisk (*) are additional Nadcap requirements.

NOTE:

 Applicable definitions can be found inAC7101/1 General Requirements for Laboratories.

2.5

Tests Audited: TEST CODE

CHECKLIS T

TEST TYPE

EQUIVAL ENT TEST METHODS

M1

AC7101/5

Hardness HB

ASTM E10

ISO 6506

EN ISO 6506

M2

AC71 AC7101 01/5 /5

Hard Hardne ness ss HR

ASTM AS TM E18 E18

ISO ISO 6508 6508

EN ISO ISO 6508

M3

AC7101/5

Hardness HV

ASTM E92

ISO 6507

EN ISO 6507

PRI operating procedures provide that "This report is published by PRI to advance the state of technical, engineering, and quality sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there from, is the sole responsibility of the user." PRI invites your written comments and suggestions. Copyright 2011 Performance Review Institute. All rights reserved. t-frm-15

01-Jan-11

PRI

AC 7101/5

2.6

Revision C

-2-

*External Proficiency Testing (PT) and Internal Round Robin (RR) Programs: TEST TYPE

NONE

INTERNAL RR

EXTERNAL PT

Brinell Hardness (HB) Rockwell Hardness (HR) Vickers Hardness (HV) Other  (List)

Reference Appendix B per AC7101/1 for the requirements relative to External Proficiency and Internal Round Robin Testing. 2.7

The laboratory shall maintain an equipment inventory list used for acceptance testing of material with the following information: a. b.

c.

NO

YES

NO

YES

NO

Laboratory Name Testing Equipment Hardness Type Location (lab or shop) Digital, Analog (Dial) or Brinell scope Scales or Brinell loads used Equipment Calibration Frequency Indenter Type(s) Inspection Frequency

3.0

PROCEDURES AND DOCUMENTS

3.1

Written instructions shall cover the following testing variables: a.

YES

Number of impressions for each test value reported.

Refer to section 10.5 for indentation spacing requirements. b.

Reading techniques for non-digital readout testing.

*Reading techniques fo r non -digital readout testing (e.g. parallax cons iderations in reading Rockwell dials).

3.2

c.

Daily verification process and recording of results.

YES

NO

d.

Preclude the use of correction factors to compensate for machine error.

YES

NO

Written procedures cover operator options for hardness re-test. (Some operator discretion is permitted)

YES

NO

Hardness Re-Test: Because problems s uch as sp ecimen wobbl ing may occ ur w hich are apparent only to the operator and only at the time of testing, operators may choose to di sregard test impressions th ey suspect of being irregular. Provided two additional impressions are made, both of wh ich give conformin g values and whos e variations are typical for the material and hardness procedure, the suspect test may be disr egarded and need not be recorded in the log or o n the certificate.

PRI

AC 7101/5

3.3

Revision C

Written procedures cover hardness referee test. (May be checked against applicable standard test methods.)

-3-

YES

NO

The laboratory s hall have a procedure addressing Hardness Referee tests, which includes at least o ne of th e following: a. b.

Re-preparation of the specimen to improve surface finish, parallelism, and/or flatness. When “ alternate” test methods are permitted, use of a hardness method or scale that best represents the material being tested: for example. Use of spherical ind enter methods w hen material is wo rk-hardenable. Use of Brinell hardness on castings o r other large-grain material. Use of Brinell hardness when “ Brinell or alternate” is specified. Selection of load whi ch produ ces maximum sensitivity of readings (higher loads for higher hardnesses). Use of direct-reading digital equipment instead of equipment requiring human interpretation of readings. Make three or five impressions. All readings should conform to specification; report at least the median value. • • • •

c. d.

NOTE:

Median is used because it is an actual test reading.

4.0

PERSONNEL AND TRAINING

4.1

Verify personnel training for one testing discipline. Function: Equipment op erated:

4.2

Training is documented.

YES

NO

4.3

Required training is referenced via the Quality Manual.

YES

NO

4.4

Training includes testing of irregular shapes, soft materials, and any special applications.

YES

NO

4.5

Operators who read test machine dials or microscopically measure indentations shall be evaluated against other operators for consistency.

YES

NO

5.0

FACILITIES AND EQUIPMENT

5.1

Hardness equipment is capable of performing the tests in accordance with all applicable requirements.

YES

NO

Hardness testing equip ment shall be designed to ensure that the force of the indenter is applied smoo thly, and witho ut impact (overload) forces being applied. The base of the equipment shall be constr ucted such that it is sufficiently ri gid to r eact to the test load, with no rocking or lateral movement of th e specimen. For Brinell hardness testing, the system ut ilized shall dampen acceleration of the load as it approaches the intended level. 5.2

The supplier has a written preventive maintenance plan in place.

YES

NO

5.3

The preventive maintenance plan is followed and logged.

YES

NO

Review plan and log for p reventive maintenance.

PRI

AC 7101/5

Revision C

-4-

6.0

CALIBRATION

6.1

Calibration records are available.

YES

NO

6.2

Records show calibration is traceable to national standards (NIST, UKAS, etc).

YES

NO

6.3

The calibration is performed in accordance with all applicable requirements.

YES

NO

6.4

A review of the calibration certificates by the QA function or the defined technical representative has been performed and documented.

YES

NO

6.5

All indenters shall be serialized. When it is not practical to mark the serial number on the indenter due to size limitations, the serial number shall be marked on the container. (Rockwell only)

YES

NO

Indenters cons ist of: 1, Ball indenters whic h frequently consis t of a holder, a cap and a ball. A ball indenter holder shall have a serial number. 2, Diamond indenters. A diamond indenter shall have a serial numb er. 7.0

MATERIAL IDENTIFICATION AND CONTROL

7.1

Using general questions from PRI AC7101/1, verify through specific jobs in process that this area complies.

YES

NO

 A u ni qu e set of id ent if yi ng nu mb ers sh all be as si gn ed t o eac h t est , to ens ur e tr aceab il it y fr om th e cer ti fi cat e issued to the custom er order, material tested, test methods used, test results and orig inal cutting plan. The laboratory’s systems shall provide for tracking and accountability of all specimens. Specimens shall be stamped, tagged or oth erwise identified to avoid inter-mixing, and shall remain identifiable until disposal. 8.0

AL TERNATE METHODS, HARDNESS CONVERSIONS

8.1

Alternative methods are used only if permitted by one of the following (Check all applicable items below):

YES

NO

YES

NO

YES

NO

Material specification Other as described below:

8.2

Hardness conversions are performed to:  ASTM E 140 ISO 18265 Other documents (describe below):

8.3

A conversion chart is used if one of the following conditions exist:  Alloy groups not covered by ASTM E 140 Work-hardenable materials (these may be noted if Rockwell hardness testing shows needle movement more than 2 seconds after the loading lever has stopped moving, or if ASTM E 140 conversion values do not hold true when load is changed for the same indenter).

PRI

AC 7101/5

Revision C

-5-

Castings and other coarse grained material (in general, indentations should include several grains) using microhardness in lieu of Rockwell or Brinell, or vice versa.  Alternate hardness methods, as described below Describe:

8.4

When conversion is used, the inspection records show the measured values as well as the converted values (i.e. conversion from another hardness scale or from tensile test).

YES

NO

Prior to us e of ASTM E140 or other co nversions, a conversion report is r equired (primary versus equivalent method) for the following:  Al lo y g ro up s n ot co ver ed b y ASTM E140. Work-hardenable materials. Castings and ot her coarse-grain materials. Microhardness in lieu of Rockw ell or Brinell; or vic e versa. • • • •

 Al ter nat e har dn ess met ho ds in co rp or ati ng aut om ati c t est mac hi nes sh all val id ate s of tw are p erf or mi ng har dn ess conversions to ensure adherence to ASTM E140. 9.0

CERTIFICATE OF TEST / CONFORMANCE

9.1

Test reports shall include all information required by the applicable industry standard/material specification and customer specification/requirements.

YES

NO

For Brinell only wh en using a Type A measuring device a statement must be inclu ded on the test certificate to the effect that a Type A measuring device w as used. 9.2

If conditions are other than normal operating conditions (ball diameter/load/load time/etc.), those conditions are reported as required.

10.0

HARDNESS VERIFICATION

YES

NO

The Auditor is to ch eck several standard test block s. 10.1

Prior to verification, the operator checks the anvil/fixture to ensure the absence of damage or foreign material.

YES

NO

10.2

Standard blocks are available for the scales and loads that are to be used for testing.

YES

NO

Hardness block identification shall consist of the following:  An of fi ci al m ark on th e tes t s ur fac e or th e th ic kn ess to an ac cu rac y of ±0.005 in ch es (0.1 mm), to v eri fy the original surface has not been ground . The surface shall be uniformly polish ed, and free from scratches that may affect current in dentation. Each blo ck shall b e marked w ith the serial number tr aceable to its certification, the mean hardness value, tolerance (if given) and the supp lier’s identification. •

•

10.2.1

Standard blocks appear to be in a condition suggesting acceptable verification, including:

10.2.1.1

Surfaces are not re-ground/re-polished.

YES

NO

10.2.1.2

Indentations are only on the allowable test surface.

YES

NO

PRI

AC 7101/5

Revision C

-6-

10.2.1.3

At least one test block shall be used, and when commercially available, the hardness range of the test block shall be chosen to be within 15 Rockwell points of the hardness value that the testing machine is expected to measure. (Rockwell only)

YES

NO

10.3

The hardness tester is periodically checked against standard test block(s) at the following minimum frequencies:

10.3.1

*Once each working shift during which acceptance testing will be performed.

YES

NO

10.3.2

* When load, anvil, or indenter are changed (Prior to each test run, defined as testing of materials using the same equipment set-up while the machine is under the control of the same operator).

YES

NO

Whenever the load, anvil or indenter is changed, and before the machine is checked w ith a test bloc k, the technician shall visually inspect the anvil and indenter. Preliminary indentations (may be on scrap stoc k) shall be made to ensure seating of the anvil and in denter. Brinell and Vickers: 1 indentation minimum Rockwell: 2 indentations minimum • •

The Operator shall ins pect the equipment prior to the periodic check, to ensure that there is no damage. This inspection s hall include anvil and indenter. Frequency: Check once each worki ng shift during w hich the tester will be used. 10.4

Hardness tester periodic checks are recorded and the test block identified.

YES

NO

Periodic c hecks shall consis t of at least two i ndentations for Brin ell and Rockw ell and five indentations for Vickers. All individu al test block readings must be within +/- tolerance of the standard test block. Averaging of the reading is not to b e used as acceptance criteria for the daily verification process. 10.5

Indentations are spaced (center to center, center to edge of block, etc.) at acceptable distances per the given test method, unless marked to disregard. METHOD Brinell Rockwell Vickers

CENTER TO CENTER 3 3 2½

2½ 2½ 2½

Diameters for Brin ell and Rockw ell. Diagonals for Vickers.

11.0

BRINELL HARDNESS TESTING

11.1

Brinell Equipment Periodic Checks

11.1.1

Periodic checks have been performed to the loads that have been used.

11.2

Brinell Set-Up Periodic Check (Before Acceptance Testing of Material)

11.2.1

The periodic verification records are current and complete.

11.3

Specimens for Brinell Testing

NO

CENTER TO EDGE

NOTE:

See gui dance in s ection 10.4.

YES

N/A

YES

NO

YES

NO

PRI

AC 7101/5

Revision C

-7-

11.3.1

The thickness of the specimen tested is such that no bulge or other marking shows the effects of the test force on the side opposite the indentation. (As a general rule, the thickness should be at least 10 times the depth of the indentation).

YES

NO

11.3.2

When indentations are made on a curved surface, the minimum radius of curvature of the surface shall be two and a half times the diameter of the indenter ball.

YES

NO

11.3.3

The angle between the indenter force line and the surface of the specimen is a right ange / perpendicular. (To verify compliance, the difference between the smallest and largest diameter readings of the same indentation shall be less than 0.1mm (0.004”).

YES

NO

11.4

Brinell Test Cycle (For one indentation)

11.4.1

Selection of the load and indenter ball diameter is determined using the applicable standard in order to produce an indentation diameter in the range of 24 to 60% of the ball diameter.

YES

NO

11.4.2

The major load is applied steadily, without a jerk.

YES

NO

11.4.3

Load is applied for a time of 10 to 15 s unless otherwise required by the product specification.

YES

NO

11.4.3.1

If test conditions are different than a 10 mm indenter, 3000 kgf scale and 10s to 15s dwell time, the indenter diameter, test force, an d dwell time are reported.

YES

NO

11.5

Brinell Hardness Readings

11.5.1

For each indentation two readings shall be taken 90 degrees apart around the diameter of the indentation and the mean is used to calculate hardness. (NOTE:  Automated test machines may convert from indentation depth.)

YES

NO

12.0

ROCKWELL HARDNESS TESTING

N/A

12.1

Rockwell Equipment Periodic Checks and Calibrations

12.1.1

The hardness test blocks being used are appropriate for the materials being tested. (see 10.2.1.3)

YES

NO

12.1.2

When the operator reads an analog dial, operator training ensures that parallax (line of site) error is not introduced.

YES

NO

12.1.3

Internal procedures address items 12.1.1 through 12.1.2 above.

YES

NO

12.1.4

The periodic verification records are current and complete.

YES

NO

12.2

Manual Control (if applicable)

12.2.1

The Minor Load is applied smoothly to reach +/-5 divisions of the “SET” position before re-setting the dial to zero.

YES

NO

12.2.2

The Major Load is removed as defined in the applicable testing specification.

YES

NO

12.2.3

If times greater than stated in the application testing specification are used, those times are specified in the product specification.

YES

NO

12.2.4

Any dwell time greater than that required by the applicable testing specification shall be recorded and reported after the test results.

YES

NO

PRI

AC 7101/5

Revision C

12.3

Hardness Readings

12.3.1

Non-Optimum specimens, such as large parts which require special fixtures or parts of irregular geometry, may be used only for tests which require minimum limits only.

-8-

YES

NO

*A minimum of tw o indentations sh all be made and compared for consis tency to insure that the specimen did not move. 13.0

VICKERS HARDNESS TESTING

13.1

Vickers Equipment Periodic Check

13.1.1

At least five hardness readings have been made on a standard test block on the scale and at the hardness level at which the machine will be used.

13.2

Specimens for Vickers Testing

13.2.1

The surface of the specimen is sufficiently smooth enough to permit the reading of the indentation diagonal to 0.0005 mm (0.00002”).

N/A

YES

NO

YES

NO

For Vickers, the accuracy to measure the diagonals shall be within ±0.0005 mm or ±0.5%, whichever is larger. 13.2.2

Corrections for radii of curvature (spheres, cylinders) are made in accordance with the applicable standard.

YES

NO

13.2.3

The periodic verification records are current and complete.

YES

NO

13.3

Vickers Test Cycle for One Indentation

13.3.1

Magnitude of test is from 1 to 120 kgf.

YES

NO

13.3.2

Magnitude of test load is reported.

YES

NO

13.3.3

Test load is applied and removed smoothly. Load is applied for a time of 10 to 15 seconds, unless otherwise required by the product specification.

YES

NO

13.3.4

Time used is reported if other than 10 to 15 seconds.

YES

NO

13.4

Vickers Hardness Readings

13.4.1

For each indentation, two diagonals at 90° are measured and the mean used to calculate hardness.

YES

NO

PRI

AC 7101/5

Revision C

EXPLANATION SHEET

PARA NO.

COMMENT

-9-