crusher guages

Ministry of Defence

INTERIM

Defence Standard

13–36 (PART 8) / Issue 1 8 February 1991

BALLISTIC STANDARDIZATION OF

GUN AMMUNITION

PART 8: CRUSHERS AND CRUSHER GAUGES

This Defence Standardsupersedes

Defence Standard 13-84/Issue 1dated 23 October 1974

DSTAN

Please see last few pages for details of the proposal for improvement.

DEF STAN 13-36 (PART 8)/1

AMENDMENTS ISSUED SINCE PUBLICATION

AMD NO DATE OF TEXT AFFECTED SIGNATURE &ISSUE DATE

Revision Note

This Standard incorporates and updates the content of Def Stan 13-84/1 andprovides additional information on the Mk 8 and Mk 9 crusher gauges.

Historical Record

Def Stan 13-84/1 dated 23 October 1974.



CRUSHERS AND CRUSHER GAUGES

PREFACE

This Defence Standard supersedes andincorporates Def Stan 13-84/Issue 1,

dated 23 October 1974

i This Defence Standard specifies the crushers (copper balls) and theassociated gauges for measuring peak internal ballistic pressures inmortars, guns and howitzers by the Navy and Army Departments of theMinistry of Defence.

ii This Standard has been agreed by the authorities concerned with its useand shall be incorporated whenever relevant in all future designs,contracts, orders etc and whenever practicable by amendment to thosealready in existence. If any difficulty arises which prevents applicationof the Defence Standard, the Directorate of Standardization shall beinformed so that a remedy may be sought.

iii Any enquiries regarding this Standard in relation to an invitation totender or a contract in which it is invoked are to be addressed to theresponsible technical or supervising authority named in the invitation totender or contract.

iv This Standard implements NATO STANAG 4113. A description of theanalysis of results of the gun firing calculations specified in the STANAGis contained in Annex B.

v This Standard has been devised for the use of the Crown and of itscontractors in the execution of contracts for the Crown and, subject to theUnfair Contract Terms Act 1977, the Crown will not be liable in any waywhatever (including but without limitation negligence on the part of theCrown its servants or agents) where the Standard is used for otherpurposes.

vi This Defence Standard is being issued as an Interim standard and isprovisional in order to obtain information and experience of itsapplication. This will then permit the submission of observations andcomments from users, using DGDQA form 0825 enclosed.

vii A review of this Interim standard should be carried out within12 months of publication. Based on the comments received the author and/orcommittee responsible for the preparation of the Defence Standard shalljudge whether the Interim standard can be converted to a normal standard ordecide on what other action can be taken.

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CONTENTS

Preface

Section One. General

1 Scope2 WARNING3 Related Documents4 Definitions

Section Two. Crushers (Copper Balls)

5 Description6 Annealing7 Calibration8 Packaging

Section Three. Mk 8 and Mk 9 Crusher Gauges

9 Description10 Dimensional Drawings11 Method of Handling

Annex A Calibration ProceduresAnnex B Analysis of Results and Preparation of Tarage TablesAnnex C Dynamic Test ProcedureAnnex D Static Test ProcedureAnnex E Sampling Plan

PAGE

1

3335

6677

889

A-1B-1C-1D-1E-1

2


Section One. General

1 Scope

This Defence Standard specifies requirements for the crushers (copperballs) and associated gauges used in measuring peak internal ballisticpressures in mortars, guns and howitzers.

2 WARNING

This Standard calls for the use of substances and/or procedures that may beinjurious to health if adequate precautions are not taken. It refers onlyto technical suitability and in no way absolves either the supplier or theuser from statutory obligations relating to health and safety at any stageof manufacture or use.

3 Related Documents

3.1 The following documents andStandard:

BS 6017

Metals AdvisoryMemorandum 268/67

Ordnance BoardProceeding No 40736Annex A

Standard OperatingProcedure No 59

MP 222

Drawing List No CM 8815

Drawing List No CM 1366A

RARDE(FH) Drawing NosGR/47340A to GR/47349 Inclusive

RARDE Drawing GR/47413A

publications are referred to in this

Copper Refinery Shapes

Lot 4: 1967 – Coppers, Crusher, Ball

Lot 4: 1967 - Coppers, Crusher, Ball

Mk 8 and Mk 9 Crusher Gauges

Measurement of Gun and Mortar InternalBallistic Pressures - Part 1 - Gauges,Crusher, Ball Mk 8 and Mk 9 dated10 January 1975

For Manufacture of Mk 8 Gauge

For Manufacture of Mk 9 Gauge

Details of Drop Guide Apparatusand the Oil Vessel

Compression Rig for Testing 3/16 inchCopper Crushers

3.2 Reference in this Standard to any related documents means in anyinvitation to tender or contract the edition and all amendments current atthe date of such tender or contract unless a specific edition is indicated.

3


3.3 Related documents may be obtained from:

DOCUMENT SOURCE

BS 6017 British Standards InstitutionSales DepartmentLinford WoodMILTON KEYNES MK14 6LE

Metals Advisory Royal Armament Research &Memorandum 268/67 Development Establishment (RARDE)

Fort HalsteadSEVENOAKSKent TN14 7BP

Ordnance Board Secretary, Ordnance BoardProceeding No 40736 Empress State BuildingANNEX A Lillie Road

LONDON SW6 1TR

Standard Operating Director of Proof and ExperimentalProcedure No 59 Establishments

St Christopher HouseSouthwark StreetLONDON SE1 0TD

MP 222 DGDQA/PSDand drawings Royal Arsenal West

WoolwichLONDON SE18 6ST

Drawing List No CM 8815 CDIADrawing List No CM 1366A Royal Arsenal West

WoolwichLONDON SE18 6ST

RARDE(FH) Drawing Nos RARDEGR/47340A to GR/4734 inclusive Fort HalsteadRARDE Drawing GR/47413/A Sevenoaks

Kent TN14 7BP

4


4 Definitions

For the purpose of this Defence Standard the following definitions apply:

4.1 Accuracy of a gauge is its ability to record or measure the “true”pressure without systematic error or bias. It may depend on pressurelevel, temperature or both. For the purposes of this Standard thecalibration curves obtained under annex B for use at -46°C, -33°C, -5°C,21°C, 52°C and 63°C shall be regarded as accurate in that any systematicerrors due to the crusher gauges have been removed. The deviation of anyindividual results from these curves is then due to random variation in thecrusher gauge, random variations in the transducer system or systems, andcurve fitting errors. Any systematic error associated with the transducersystems will result in a displacement of the calibration curve from the

cannot be assessed.

4.2 Precision indicates firstly the consistency of output of an individualgauge throughout its life and secondly the consistency of output of several

"true" pressure curve but unfortunately the amount of this displacement

gauges of the same type. It is also called reproducibility. With goodprecision there will be little spread of results from several gauges ofsame type subjected to the same pressure cycle.

Precision shall be assessed as the standard deviation of results fromseveral gauges of the same type in one round, about their mean. When

the

several rounds of one type are fired, an average value of precision shallbe calculated by taking the root mean square of the standard deviationsfrom all these rounds weighted according to their individual degrees offreedom.

(ml -1)S1

2 + – - - - +(mt –l)St

2

S2 = ------------ (1)

(ml + m2 + - - - mt)-t

where S1 to St = standard deviation for rounds 1 to t

S = average standard deviation for all rounds 1 to t

m 1 to mt = number of gauges for rounds 1 to t

t = number of rounds

4.3 True pressure. Is that value of maximum gas pressure which actuallyexists and would be obtained from an ideal measuring system. For presentpurposes modern transducer systems which record pressure as a time functionare accepted as giving the best available estimate of “true” pressure.

5


Section Two. Crushers (Copper Balls)

5 Description

5.1 The crushers used in the UK crusher gauge are precision balls madefrom oxygen-free copper. Before firing, a crusher, enclosed in a crushergauge, is inserted in the chamber of the gun. After firing, the remaininglength of the deformed crusher is measured and from this the pressuredeveloped in the chamber of the gun can be determined.

5.2 Material. The crushers shall be manufactured from oxygen-free, highconductivity copper containing:

(a) Not less than 99.95% copper

(b) Not more than 0.005% oxygen

(c) Not more than 0.003% silver

or, alternatively, in accordance with BS 6017.

5.3 Dimensions. The crushers shall be spherical and conform to thefollowing dimensions:

The lot mean ball diameter may be between 4.7244 mm and 4.7752 mm. Thespread about the mean shall not exceed ± 0.0051 mm.

5.4 Dimensional inspection. The crushers shall be measured in accordancewith a sampling plan prepared by the Contractor, based on the defectclassification list shown in annex E.

5.5 Lot and batch size. The number of crushers constituting a lot shallbe not less than 250,000 to be delivered in batches of approximately25,000. The complete lot of crushers shall be produced from the same castof copper.

5.6 Identification of lots and batches. Each batch shall be allotted aserial number.The first digit or two digits shall be the lot number andthe last two digits shall be the number of the batch; thus batch No 507will be the seventh batch in lot No 5.

6 Annealing

6.1 Pre-annealing treatment. If the copper crushers are finished to sizein conjunction with steel balls they shall be pickled in ambient 10%sulphuric acid solution for two minutes, then washed and dried. Otherwisethey may be pickled after annealing to remove any discolouration.

6


6.2 The crushers shall be annealed in batches of approximately 25,000 in acontrolled temperature heating chamber at a temperature of 425°C + 3°C for30 minutes. The heating time shall not start until a thermocouple housedin the vessel indicates that balls at the centre of the vessel have reachedthis temperature. To assist in this, the vessel may be of any convenientshape (annular, rectangular, cylindrical, spherical, etc) but care shall betaken that dimensions are such that geometry of the vessel allowsrelatively quick heating of balls at the centre of mass. The balls shallbe housed in a vessel purged of air and filled with an inert gas (argon) ata pressure of two atmospheres. After heat treatment the vessel shall beremoved from the heating chamber, re-pressurized immediately with the inertgas and allowed to cool in still air to room temperature.

6.3 The copper balls may be cleaned by pickling in cold 10% sulphuric acidfor two minutes, then washed in water and dried, if they have becomediscolored during their manufacture.

NOTE: To ensure the closest inter-batch hardness comparisons, the equipmentand procedure described in Metals Advisory Memorandum 268/67 (see section3.1) should be followed.

7 Calibration

Each new lot of crushers (copper balls) shall be calibrated with the objectof producing a set of tarage tables for use with that lot only. Proceduresare detailed in annex A.

8 Packaging

8.1 After annealing, the copper balls are to be packed in batches (5.5)and protected against damage that may occur during handling, transportationand storage. The balls are to be packed in sub-packages of 50 balls (or asotherwise agreed by the Quality Assurance Authority which will be stated inthe Contract). The packaging must be capable of storing the ball withoutdegradation, for a minimum of 15 years.

8.2 Package marking. Each pack must be marked with the followinginformation:

COPPER CRUSHER BALL - LOT NO:BATCH NO: . . . . . . . . . . . . . . . . . . . . . . . . . . .QTY : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .CONTRACTOR’S NAME: . . . . . . . . . . . . . . . . . .CONTRACT NO: . . . . . . . . . . . . . . . . . . . . . . . .

7


Section Three. Mk 8 and Mk 9 Crusher Gauges

9 Description

Both UK crusher gauges, (Mk 8 and Mk 9) consist of a cylindrical steel bodyin which a 4.76 mm diameter copper ball (the crusher) is positioned betweena piston at one end and an anvil which acts as a closure cap at the other.In the Mk 8 gauge the piston slides in a bore in the gauge body, while inthe Mk 9 gauge the piston slides in a bore in a second cap screwed into theother end of the body. The gauge or gauges are positioned towards the rearend of the barrel, where they are exposed to the propellant peak gaspressure which acts on the piston to compress the crusher upon firing. Thedeformation of the crusher, measured by its remaining length, enables thegas pressure at that position to be determined.

10 Dimensional Drawings

10.1 Mk 8 gauge. The Mk 8 gauge is manufactured to the followingdrawings:

Drawing List No: CM 8815NATO Stock No: 5220-99-109-2864

ITEM NAME DRAWING NO

Body, gaugeAnvil, crusherPistonFrame, centring gaugeSpring

CM 9111CM 9112CM 9113CM 8816CM 8817

10.2 Mk 9 gauge. The Mk 9 gauge is manufactured to the followingdrawings:

Drawing List No: CM 1366ANATO Stock No: 5220-99-963-1055

ITEM NAME DRAWING NO

Body, gaugePistonCap, piston guideAnvil, crusherFrame, test pieceWasher, non-metallic

CM 8888CM 8889CM 8890CM 8891CM 8892CM 8893

8


10.3

10.3.1

Gauge Inspection

For calibration firings of a new lot a more rigorous dimensionalcheck of the bore and the piston over their engaged length shall be carriedout. Only those gauges shown to be within manufacturing tolerance will beused. A measuring system having a resolution of 2 microns or better shallbe used for these requirements.

10.3.2 During routine use gauges shall be visually inspected (Piston/Bore)for signs of erosive wear. Gauges which show signs of erosive wear shouldno longer be used.

11 Method of Handling

Detailed handling instructions for the two gauge types are specified inStandard Operating Procedure No 59. It should be noted that a crushergauge is a precision scientific instrument and should be handled as such.Where possible the gauge body, piston and screw cap(s), should remainunique to each gauge and not intermixed between gauges. Gauge assemblyshould be done in a clean room with a dust-free atmosphere, as dirt insidea gauge may cause deterioration or actual damage leading to obturationfailure of the gauge.

9

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DEF STAN 13-36 (PART 8)/1ANNEX A

Calibration Procedures

A.1 Procedures

A.1.1 Stages. Each new lot of crushers (copper balls) shall be calibratedwith the object of producing a set of tarage tables for use with that lotonly. The work shall be carried out in three stages as follows:

(a) Static loading of a number of crushers from each batch so that aStandard Batch may be nominated as representative of the lot. In this,test balls from all batches will be subjected to similar static loads whenthe “hardness” of the balls from each batch will be indicated by theremaining length of the deformed balls. The balls from the Standard Batchwill have a remaining length in the middle of the overall range for thewhole lot.

(b) Dynamic loading of a number of crushers from each batch in turntogether with an equal number of crushers from the Standard Batch (see (a)above) to enable the variation in dynamic compressibility between thebatches to be established.

(c) Gun firings using crushers from the Standard Batch in Mk 8 and Mk 9gauges to obtain data from which the tarage tables willannex B).

NOTE : Stages (b) and (c) may take place concurrently.

A.1.2 Static loading. One of the following static loading tests shall beused:

A.1.2.1 Twenty crushers from each batch shall be individually subjected tostatic loads of 400 kg ± 0.4 kg between parallel faces at a compressionrate of not more than 0.5 mm per second in a suitable compression machine.The remaining length of each compressed crusher shall be measured to anaccuracy of 0.0025 mm. The mean remaining length and standard deviationabout the mean for each batch and the lot mean (average of the batch means)shall be calculated. Alternatively, the procedure detailed in A.1.2.2 maybe used.

A.1.2.2 For this test a reference batch shall be selected at random.Using the apparatus described in annex D, a set of nine crushers from thebatch under test shall be subjected to the same load in a suitablecompression machine able to deliver loads of 4 tonnes at a compression rateof not more than 0.5 mm per second. Four such tests shall be performed oneach batch in turn, ie 36 crushers of the Test Batch. The remaininglengths of all the compressed crushers (Test and Reference Batches) shallbe measured to an accuracy of 0.0025 mm. For each individual test the meanremaining length and the standard deviation about the mean of the Test andReference Batches shall be calculated and the average difference test mean- reference mean for the tests determined and recorded. The average mean

difference for the whole lot shall also be calculated.

A.1.2.3 The Standard Batch shall then be selected as follows:

For test A.1.2.1 the batch whose mean is closest to the lot mean remaininglength is taken; or for test A.1.2.2 the batch whose mean difference isclosest to the lot mean difference is chosen. If the lot mean differenceis zero then the Reference Batch shall be taken as the Standard Batch.

A-1

DEF STAN 13-36 (PART 8)/1ANNEX A (Continued)

A.1.3 Dynamic laboratory loadings. The equipment and procedure describedin annex C shall be used to provide simultaneous dynamic loadings ofStandard Batch crushers and crushers from each of the other batches in turnto provide a comparison of the dynamic compressibility of the StandardBatch with each of the other batches. The results of these tests will beexamined by the Ministry of Defence Approving Authority (RARDE FortHalstead) who will recommend which batches can be represented by theStandard Batch and a procedure for dealing with any other batches (such asby the formation of a new lot or lots with their own modified taragetables).

A.1.4 Gun firing calibrations. Gun firings shall be carried out usingStandard Batch crushers in Mk 8 and Mk 9 crusher gauges as detailed inA.1.4.1. The chamber gas pressure-time histories shall be recorded foreach round fired using two transducer pressure measuring systems operatingas independently as possible from one another. A common voltage or chargecalibration may be used for the two systems. {If two systems usingtransducers based on different physical principles are available this wouldbe preferred.} The measuring systems shall have a frequency response fromDC to at least 20 kHz ± 3dB. The transducers shall be located in thechamber such that there is no expected difference in their recordings, ieat the same distance from the breech face. The mean value of the tworeadings will be accepted as the true pressure if they do not differ bymore than 2%. Should the values differ by more than 2%, the crusher gaugeresults may be used only to establish crusher gauge precision.

An allowance shall be made for pressure gradient when necessary if thecrusher gauges and the transducers are not located in the same section ofthe chamber.

The crusher gauge shall be carefully dismantled without delay following afiring and the remaining length of the copper crusher measured in units of0.0025 mm with a measuring instrument having a resolution of 0.0025 mm orbetter. The transducer chamber pressures will be recorded against theremaining length of the crushers in tabular form.

A.1.4.1 Firing programme. For each temperature (see A.1.4.2 and A.1.4.3)the firing programme shall be:

(a) Mk 8 gauge. Rounds shall be fired in a suitable weapon with four Mk 8gauges per round at pressure levels from 200 bars to 2200 bars inapproximately 100 bar increments. If two weapons are required to achievethis pressure range there shall be an overlap of 200 bars of pressurebetween the two weapons. A total of 21 to 24 rounds shall be fired.

(b) Mk 9 gauge. Rounds shall be fired in a suitable weapon with six Mk 9gauges per round at pressure levels from 1500 bars to 6250 bars inapproximately 250 bar increments. These rounds shall be fired in twodifferent weapon types (eg an artillery gun and a high performance tankgun) with a pressure overlap of approximately 500 bars. A total of 23rounds shall be fired.

NOTE 1: Additional rounds may need to be fired if any pressure intervalbetween adjacent rounds exceeds 12.5% of the pressure range for the gauge.In this event the appropriate Ministry of Defence Approving Authority(RARDE Fort Halstead) should be informed and they will advise.

A-2

DEF STAN 13-36 (PART 8)/1ANNEX A (Concluded)

A.1.4.1 (Contd)

NOTE 2: Rounds with pressures in the range 1500 bars to 2200 bars may beused for Mk 8 and Mk 9 gauges simultaneously.

A.1.4.2 21°C tarage table. The basic pressure versus remaining lengthfunction shall be calculated as given in annex B using data from theprogramme rounds fired at 21°C and a tarage table prepared.

A.1.4.3 Temperature corrections. The firing programme (A.1.4.1) shall berepeated using gauges conditioned to -46°C, -33°C, -5°C, 52°C and 63°C toenable the gauge/crusher performance to be established throughout theoperational temperature and pressure range.

The charges will be conditioned to 21°C. The gauges must be maintained atthe required conditioned temperatures after loading into the weapon chamberup until fired.

Using the data from these rounds and the rounds fired at 21°C, taragetables shall be calculated for the full range of temperatures at 10°Cintervals (from -40°C to 60°C) as well as at the individual firedtemperatures as given in annex B.

Further, if the gun/charge system permits, two or three sets of gaugesconditioned to different temperatures may be used in single rounds. Thiswill allow either a substantial saving in ammunition costs or additionaltemperature levels to be examined, or both.

A.2 Preparation of tables. The data obtained in subclauses A.1.2, A.1.3and A.1.4 above shall be forwarded to the appropriate Ministry of DefenceApproving Authority (RARDE Fort Halstead) who shall act as advisers asrequired throughout the production, calibration and analysis processes.

A-3

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DEF STAN 13-36 (PART 8)/1ANNEX B

Analysis of Results and Preparation of Tarage Tables

B.0 The following analytical procedures for the dynamic firing tests arein general agreement with annex D of STANAG 4113 where appropriate.

B.1 Regression Functions

Using a least squares regression technique, third order regressionfunctions of remaining length of crusher on corrected piezo pressure,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (2)

corresponding remaining lengths for all fired temperatures.will be calculated using all valid piezo pressures and the

where ====

=

B.2 Outlier Test

fired temperature1, 2,........,n and n = number of rounds1, 2,........,m and m = number of gauges per roundthe mean recorded transducer pressure corrected forpressure gradientthe crusher remaining length for temperature roundNo i and gauge No k.

The standard deviation of the observed remaining lengths about theregression function, defined as

shall also be calculated for each temperature.

Individual results which do not satisfy the following test

where fitted remaining length using in regression equation (2),shall be designated “outliers” and shall not be used in calculating thecorrected regression functions below.

B.3 Corrected Regression Functions

Third order regression functions of remaining length on corrected piezopressure using and excluding outliers) data,

(5). . . . . . . . . . . . . . . . . . . . . . . . . . .

will be calculated.

B-1

DEF STAN 13-36 (PART 8)/1ANNEX B (Continued)

B.4 Tarage Tables (at Fired Temperatures)

B.4.1 Tarage tables of crusher pressure PCR against crusher remaininglength will be constructed for the full pressure range of the crusher gaugeat intervals of 0.01 mm for the Mk 8 gauge and 0.0025 mm for the Mk 9 gaugein remaining length from the corrected regression functions above for eachof the fired temperatures.

B.4.2 Tarage tables (10°C intervals). Using the corrected regressionfunctions (equation 5) obtain remaining lengths (L ) at each of 300 to500 pressure levels equally spaced through the working pressure range ofthe gauge.

Then for each pressure level calculate third order regressions of L on as:

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (6)

From this equation obtain the fitted remaining lengths at each temperature,from -40°C to 60°C in 10°C steps,

and at each fired temperature,

The fitted remaining lengths are only indirectly related to the maincorrected regression functions. To avoid inconsistencies between the twosets of tarage tables finally obtained (ie at the fired temperatures and at10°C intervals) each fitted remaining length is to be corrected oradjusted by interpolation and a pro-rata basis as follows:

RL. . . . . . . . . . . . . . . . . . . . . . . (7)

where is the temperature under consideration, and are the firedtemperatures on either side of and are the fitted remaininglengths equation(6)or temperatures and respectively, is thefitted remaining length at temperature and and are theremaining lengths obtained from the corrected regression functionequation (5) for temperatures and respectively.

This process is to be repeated at each pressure level to obtain an array ofremaining lengths, for each temperature and presure level P. Fromthese simple interpolation for each 10°C temperature pressures can beobtained for the remaining lengths of the tarage table at intervals of0.01 mm for the mark 8 gauge and of 0.005 mm for the mark 9 gauge.

B-2

DEF STAN 13-36 (PART 8)/1ANNEX B (Continued)

B.5 Accuracy Tests

For the purpose of assessing the overall accuracy of the final taragetables the transducer pressures are assumed to be “true pressures”.The tarage table values (or the stored PCR versus L and values ifrounded suitably) shall be used to obtain crusher pressure PCR foreach crusher remaining length obtained in the trials including the outliersand hence the individual errors (crusher pressure-piezo pressure) can beobtained. For each gauge the pressure range shall be divided into fourequal zones and a variation coefficient shall be calculated for each zoneand fired temperature using all the individual errors in the zone as

variation coefficient = 100. . . . . . . . . . . (8)

The piezo pressures shall be used to determine in which zone an individualresult lies.

B.6 Glossary of Terms

a b c and d

A B C and D

i

k

L

L

L

L c o r r

coefficients in remaining length on regressionequation (2)

coefficients in corrected remaining length onregression, equation (5)

round number equations (2), (3), (4), (5) and (8)

crusher gauge number equations (2), (3), (4), (5) and(8)

remaining length (RL) used generally with suffix

length variable in RL on pressure regressionequation (2)

recorded RL for temperature round number i andgauge number k equations (2), (3) and (4)

fitted RL using in equation (2)

length variable used in corrected RL on pressureregression (excluding outliers) equation (5)

B-3

DEF STAN 13-36 (PART 8)/1ANNEX B (Concluded)

m

m1 to mt

n

PCR e , i , k

P

P

P

and

L and

L

L

Lp

QP,RP,SP, and TP

RL

S

S1 to St

t

number of gauges per round equations (2) and (3)

number of gauges for rounds 1 to t equations (1), (3)and (8)

number of rounds at each temperature equations (2) and(3)

crusher gauge tarage table pressure for temperatureo round number i and gauge number k using originalrecorded remaining lengths equation (8).

corrected piezo pressure in RL on pressure regressionequation (2) and (5)

piezo-electric pressures corrected for pressuregradient for temperature and round number iequations (2) and (5)

pressure from equation (5) for RL = L (incremented RLvalue)

Temperature (in particular fired temperature)

Adjacent fired temperatures equation (7)

Tarage table temperature, -40°C to 60°C at 10°Cintervals

Fitted remaining lengths for fired temperatures andequation (7)

Fitted remaining length for temperature equation (7)

Remaining lengths for assumed pressure P equation (7)

Remaining length variable in temperature regression forpressure P equation (6)

Coefficients in remaining length on temperatureregression equation (6)

Remaining length calculated using equation (7) fortemperature and pressure P

average standard deviation for rounds 1 to tequation (1)

standard deviation for individual rounds 1 to tequation (1)

number of rounds to be averaged equation (1)

standard deviation of the observed remaining lengthsabout the regression function

B-4

DEF STAN 13-36 (PART 8)/1ANNEX C

Dynamic Test Procedure

C.1 Apparatus

C.1.1 The dynamic test apparatus comprises a 11.34 kg weight which fallsvertically in a drop guide onto a piston in the top of an oil vessel whichis positioned centrally between the guide rails. The impact of the weighton the piston produces in the oil in the vessel a pressure pulse of roughlyknown intensity and duration. The drop guide apparatus and the oil vesselare detailed in RARDE(FH) Drawing Nos GR/47340A to GR/47349 inclusive.

C.1.2 The oil vessel contains two sets of six outwards facing pistons,each set identical in size, which are exposed to the oil pressure. Theupper set of pistons are of 81 mm2 cross -section and the lower set 37 mm2.A copper ball attached by a rubber sleeve to the base of a screwed-in anvilis held in contact with the head of each piston. The pressure pulse actingvia the pistons compresses the balls between the piston and anvil faceswith transient loads which are identical within each set. With three ballsfrom each of two different batches of crushers loaded with a set, therelative dynamic compressibility of the two batches can be established atthat load level by comparing the remaining lengths of the balls.

C.1.3 To reduce any effect due to differences between pistons another dropis made from the same height with balls from the two batches interchangedin position, Two more pairs of drops are made from the same height - sixin all.

A further six drops (three pairs) are made from a greater height.Altogether in the 12 drops, 144 balls will be compressed, 72 from each oftwo batches, one of which will be the Standard Batch and the otherdesignated the Test Batch in the 12 drop test series.

C.2 Filling the Vessel with Oil

C.2.1 It is important that the oil volume in the vessel be filled with oilfree from any air bubbles as trapped air can produce undesirable pressureoscillations. The following procedure is designed to achieve this.

C.2.2 After loading the vessel with 12 uncompressed copper balls (seeclause C.3) and inserting Piezo electric Quartz Transducer (see clause C.4)remove the bleed plug adjacent to the Piezo electric Quartz Transducer andcarefully pour oil into the vessel. The use of a syringe may help toreduce air bubbles. This is best done with the vessel clamped in a vicewith its operating piston downwards and fully extended. Before insertingthe closure plug any trapped air can be expelled by gently moving theoperating piston in and out until no further bubbles appear. If any air istrapped in the channel below the Piezo electric Quartz Transducer thevessel should be tilted further to help it to escape. When all the air isremoved ensure that the operating piston is fully extended and that thereis surplus oil in the filling hole. Screw in the closure plug slowly toavoid a build-up of pressure in the oil that might distort the copper ballsand then tighten. The vessel is now ready for use. At this stage thepiston should not move into the vessel when lightly pressed.

C.2.3 Between drops, after the vessel has been reloaded with a further 12balls, the piston should be examined to see whether any significant amount

C-1

DEF STAN 13-36 (PART 8)/1ANNEX C (Continued)

C.2.3 (Contd)

of oil has escaped; the piston protrusion being less than normal by 3 mm ormore. If more has escaped the vessel should be topped up with oil asabove.

C.3 Re-loading the Vessel with Balls

C.3.1 Following a drop test the compressed balls are to be removed and anew set of balls inserted as follows. Lay the vessel on its stand withscrew caps 1 and 2 uppermost. Remove cap No 1 and the compressed ball andplace the ball in the first column in the ball tray in the row appropriateto the drop number. Insert a new ball into the retaining sleeve of the capand screw the cap back into the vessel to a torque of 8 to 10 Nm. Repeatwith cap No 2 and ball. Turn vessel until screw caps 3 and 4 are uppermostand repeat the procedure until all 12 balls have been replaced by newballs, with the 12 compressed balls in the tray.

C.3.2 For the odd number drops, balls from the Test Batch will be loadedinto holes 1 to 6 and balls from the Standard Batch in holes number 7 to12. For the even number drops this order will be reversed ie StandardBatch balls in holes 1 to 6. This will enable any difference in behaviourbetween the holes to be removed in the subsequent analysis. It should beemphasized that the correct balls must be used where required, otherwisethe test becomes valueless.

After all 12 balls have been loaded, check the piston protrusion and refillvessel if necessary (see C.2.3) before putting the oil vessel in the droprig.

C.4 Inserting the Piezo electric Quartz Transducer (see Note 1)

The vessel is designed to take a Piezo electric Quartz Transducer(see Note 1). Before the transducer is screwed into the vessel, ensurethat the seating in the vessel is clear and clean and that the sealingwasher is in position at the base of the transducer. Screw the transducerinto the vessel using the correct box spanner and tighten it tomanufacturers recommended torque.

NOTE 1: The Kistler Pressure Transducer type 6211 using seal 1101B, hasbeen used and found suitable for this application.

C.5 The Drop

C.5.1 Ensure that the release pin through the weight eye and lifting shackle is properly inserted before resetting the weight catching pawlmechanism. If this mechanism is not reset damage may be caused should theweight be released. Raise the weight to its required height (approximately1.8 m for the high pressure and 0.9 m for the low pressure drops). Connectthe Piezo electric Quartz Transducer lead to the transducer and positionthe vessel centrally between the guide rails making sure that the cable isnot trapped. Set or connect the triggering device for the electricalpressure recording gear.

C.5.2 Place a small piece of soft metal (a waste copper ball is ideal)onto the top of the closure piston to help reduce the initial transientpressure shocks that might otherwise occur with the steel to steel contact

C-2


C.5.2 (Contd)

of the weight onto the piston. Note that a length of copper wire (10 to 14SWG) may serve to reduce these shocks and also provide a suitable trigger(if insulated from earth) for the recording gear.

C.5.3 Pull the release pin allowing the weight to fall. After it hasstruck the piston, the weight should rebound to approximately half itsoriginal height. If the weight is not caught by the rachet and strikes thepiston a second time, the test should be regarded as invalid and repeated.

C.6 Pressure-time Recording

Using the Piezo electric Quartz Transducer (see Clause C.4 Note 1) andappropriate electronic apparatus a pressure-time pulse for each drop is tobe obtained. This is not intended to provide an accurate measurement ofthe peak pressure although such information may be of value later. Themain purpose is to confirm that the pressure-time pulse is smooth and freefrom spurious oscillations, particularly near to peak pressure. Suchoscillations, which would probably be due to air trapped in the vessel,could affect the compression of the copper balls and in particular theconsistency of results. The analysis of results relies on consistencybetween drops to permit the elimination of the between hole differencesthat may be present with the vessel.

C.7 Measuring the Compressed Balls

C.7.1 The remaining lengths of the compressed balls shall be measured asdetailed in Standing Operating procedure No 59. Because of the relativelysmall sample of balls to be tested from each batch compared with the batchsize (ie 72 of 25 000) and accepting that the dynamic calibration is aone-off process it is important that a reliable measurement of the ball isused in the analysis. Hence unless an automated digitized measuring systemis used, then the remaining length of each compressed ball shall bemeasured by two operators independently. The first measurement canconveniently be made as each ball is unloaded from the vessel and a secondset of measurements made later. If any pair of measurements differ by morethan 0.0050 mm then the ball shall be re-measured and an agreed figure usedin the subsequent analysis.

C.7.2 The compressed balls shall be stored in suitable containersidentified as to batch number, drop number and hole number until theanalysis of results has been completed to the satisfaction of the Ministryof Defence Approving Authority.

C.8 Analysis of Results

C.8.1 In a complete test of one batch against the Standard Batch 72 ballsof each batch will have been compressed in four sets of load levels (twooil pressure levels and two piston areas) in the 12 drops. Each load levelcomprises 18 balls of the Standard Batch and 18 balls of the batch undertest, ie six drops with three balls of each batch per drop. Within eachset of results a comparison between the 18 Standard Batch and the 18 TestBatch balls shall be made as follows:

C-3


C.8.2 The results may be represented by the following table (eg for thefirst six drops using the larger pistons 1 to 6, now numbered Hole 1 to 6for the convenience of the following table below:

Hole

Drop 1 2

The hole differences and the pressure differences can be removed to firstorder after which the other errors are accepted as part of the within-batcherrors rather than perform a full analysis of variance.

For each hole subtract the column mean from each of the entries in thecolumn in turn and then for each drop subtract the new row mean from eachof the modified entries in the row in turn. A new array will result inwhich each Test Batch result can be represented by and each

Where and are the indiviual

3 4 5 6

123456

T 1S 4T 7S10T13S16

T 2S 5T 8S11T14S17

T 3S 6T 9S12T15S18

S 1T 4S 7T10S13T16

S 2T 5S 8T11S14T17

S 3T 6S 9T12S15T18

where Tx and Sx are the means of the two readings of the remaining lengthsof the Test Batch and Standard Batch balls respectively. A further threesets of data will be provided by the set of smaller pistons (drops 1-6) anddrops 7 to 12.

C.8.3 The results above will be influenced by:

(a) the between batch difference, which we are seeking to establish.

(b) the effect of any hole difference and any hole-remaining lengthinteraction.

(c) the effect of any pressure difference between drops and anypressure-remaining length interaction.

(d) the within batch variability in compression.

(e) measurement errors.

(f) other unspecified experimental errors.

Standard Batch result byrandom errors with

C-4

DEF STAN 13-36 (PART 8)/1ANNEX C (Concluded)

C.8.3.1 Modified array:

HoleDrop 1 3 5 2 4 6

123456

etc

From these, the Test Batch mean the Standard Batch meanand the standard deviations about these means are to be calculated givingand the Test and Standard Batch standard deviations.

Four estimates of together with four estimates of the Test Batch andStandard Batch deviations are to be calculated and a mean and RMS valueof Test Batch and Standard Batch standard deviations obtained.

C.8.3.2 The results for all batches are to be summarized as a table:

Drops 1 to 6 Drops 7 to 12Batch CombinedNumber

larger holes

Test Std sd sd

smaller holes larger holes smaller holes

Test Std Test Std Test Stdsd sd sd sd sd sd

Test Stdsd sd

C-5

Blank Page

DEF STAN 13-36 (PART 8)/1ANNEX D .

Static Test Procedure

D.1 Introduction

The apparatus is used to subject two sets of nine copper ball crushers fromdifferent batches to identical static loads so that the relativecompressibility of the batches may be assessed from the remaining lengthsof the compressed crushers. One batch, designated the Reference Batch, isto be compared with each other batch in turn.

D.2 Apparatus

The apparatus consists of an anvil and a pair of plates held between thejaws of a compression machine. The anvil, a 12.70 mm thick by 50.80 mmsquare steel plate, has a set of nine 6.35 mm diameter cylindrical posts oneach side back to back, onto each of which a copper crusher is secured.

The base plate, a 25.40 mm thick by 196.85 mm by 69.85 mm steel platecarries a pair of vertical steel columns 25.40 mm diameter. The similarsized top plate has a pair of holes allowing it to slide freely up and downthe columns.

The plates are normally held apart by a pair of strong compression springslocated around the columns. The movement of the plates when forcedtogether in the press is limited by a pair of hollow rigid steel stopswhich themselves fit around the springs.

The apparatus is to be used in a compression machine which can provide aload in excess of 4.064 tonnes at a compression rate of not more than0.5 mm per second.

The apparatus is detailed in RARDE drawing GR/47413/A entitled “CompressionRig for Testing 3/16 inch Copper Crushers”.

D.3 Experimental Technique

For a single compression of eighteen balls, designated a round, nine ballsfrom one Batch are attached to the upper posts of the anvil using shortlengths of rubber tubing and nine balls from another Batch to the lowerposts. Care should be taken to ensure that the balls are located centrallyon their posts. The upper set are designated numbers 1 to 9 and the lowerset 11 to 19 with 1 opposite 11 etc.

The anvil is inserted between the plates near to, but not touching thelocating pins. When the press is operated the plates are forced togetheruntil the plates are in hard contact with the stop columns hencecompressing all the balls to approximately the same remaining length. Thefinal load will be of order 4.064 tonnes when the meter monitoring thecompressing load will indicate the load to be increasing more rapidly.

Applying the load in two phases, firstly up to approximately 1.524 tonnes,releasing the load, then applying up to the full load after checking thatthe anvil is clear of the locating pins, helps reduce the “tilt planeeffect” see later (D.5.2.1).

D-1

DEF STAN 13-36 (PART 8)/1ANNEX D (Continued) .

D.3 (Contd)

Four rounds, designated a serial, will be used in the comparison of eachBatch in turn against the Reference Batch. For rounds 1 and 3 balls fromthe Reference Batch will be on the upper posts (Nos 1 to 9) and for rounds2 and 3 Test Batch balls will be on these posts.

D.4 Measurement of Compressed Balls

The compressed balls will be measured using a micrometer with a resolutionof 0.0025 mm. Extreme care must be taken at all stages during loading,removal, measurement and storage of the compressed balls to preserve theidentity of the balls as regards their location and round number.

D.5 Analysis of the Data

D.5.1 Mean difference between Batches. The within round differencebetween the means of the nine Test Batch remaining lengths and the nineReference Batch remaining lengths is a measure of the comparativecompressibility of the two batches. The four rounds for each serialprovide four estimates of the mean difference from which an overall mean isobtained.

The first and last serials should test the Reference Batch against itselfto give an evaluation of the overall accuracy of the experimentaltechnique.

D.5.2 Variability in remaining length. It has been found that the biaserrors associated with the apparatus and the experimental techniquecontribute most to the overall error budget, that is the variability aboutmean remaining length. The errors are designated the tilt plane effect,the post effect and the level effect.

D.5.2.1 Tilt plane effect. For each round, at full compression the anvilfinished slightly non-parallel with the plates. The result is that thecompressed balls on one side of the anvil range in size from larger in onecorner to smaller in the other with the compressed balls on the oppositeside of the anvil showing a similar but opposite pattern. The planethrough the two sets of data (upper and lower) combined can be calculatedand the remaining lengths modified appropriately.

D.5.2.2 Post effect. Due to manufacturing tolerances etc there is a biaseffect between posts. This can be allowed for by averaging for each postthe observations for the four rounds of a serial and subtracting theaverage from the individual values.

D.5.2.3 Level effect. There may be a slight difference in load levelbetween the upper and lower positions. This can be allowed for bycalculating the level averages for all upper and lower remaining lengthsrespectively for all serials combined and subtracting appropriately fromthe individual observations.

D.5.2.4 Variability due to the crusher. The remaining variation afterthese three effects have been allowed for is assumed to be due to thecrusher. The Standard Deviation for each set of nine modified observationsis then calculated.

D-2

DEF STAN 13-36 (PART 8)/1ANNEX D (Continued)

D.5.2.4 (Contd)

The Standard Deviation of the mean difference (Test Batch remaining length- Reference Batch remaining length) for a serial is then obtained as theRMS average of the four standard deviation within the serial for the Testand Reference Batches respectively.

D.6 Between Batch Difference and Selection of a Standard Batch

For each Batch a (Test Batch-Reference Batch) difference will be obtainedand the overall mean difference for all Batches calculated. The StandardBatch is selected whose individual mean is close to the overall mean andwhich does not have an unusually high Standard Deviation.

As an example Table A gives the results of the Static Tests of Lot 8crushers (1989) from which Batch 816 was selected as the Standard Batch.The Reference Batch used throughout the tests was Batch 805. Table B givesthe results of the four rounds of serial No 2, Batch 801. Note, remaininglengths and differences are in imperial units of 0.0001 inch in bothTables. The imperial units in the tables will be converted to metric unitswhen the Interim Standard is given full Defence Standard status.

D-3

DEF STAN 13-36 (PART 8)/1ANNEX D (Continued)

Batch No

813

817

804

805

815

812

801

816

803

806

808

809

818

810

811

807

802

814

(all)

TABLE A

STATIC TESTS OF LOT 8 BALL CRUSHERS

(T-R) s.d (T-M)

.44 1.27 1.08

.33 1.00 .97

0 1.21 .64

-.11 .80 .53

-.14 1.18 .50

— .17 .87 .47

-.50 .82 .14

-.64 .96 -.01

-.72 1.05 -.09

-.86 1.07 -.22

-.89 .71 — .25

-.94 1.02 -.30

-1.17 1.19 -.53

-1.19 1.19 -.55

-1.28 1.01 -.64

-1.31 .90 -.67

-1.50 .71 -.86

-2.36 1.27 -1.72

-.72 1.02

s.d

1.66

1.39

1.36

.95

1.28

.98

.83

.96

1.05

1.09

.76

1.07

1.31

1.32

1.20

1.13

1.12

2.15

1.24

Batch 805 was Reference Batch

D-4

DEF STAN 13-36 (PART 8)/1ANNEX D (Concluded)

TABLE B

ANALYSIS OF STATIC COMPRESSION TESTS COMPARING BATCH NO 801WITH REFERENCE BATCH NO 805

Original Data Matrix: Test ReferenceReference Test

Serial No: 2 Test Reference

Rd No1

2

3

4

126612651263

126712651262

126512641261

1269

Upper128012781277

128212781275

128012781275

1281

Reference

129312921291

129412911290

129312921290

1292

Test

129012941297

128812941299

129112951298

1285

Lower127512801282

127512791284

127512791283

1273

126112641267

125912641269

126012641267

12621267 1278 1290 1290 1278 12661265 1276 1288 1295 1282 1269

Individual Difference from ‘Tilt Plane’ and the ‘Post Effect’ Averages

1 .26 -.22 .06 .03 -.19 .08 -.19 .33 -.15.10 -.42 .06 .08 .81 -.22 -.19 -.22 .01

2 -.21 .40 -.25 .06 -.08 -.73 .33 -.06 .54-.43 .97 -.64 .05 -.31 -.41 .28 .17 .32.13 .06 -.25 .40 .58 .27 -.33 -.40 -.46.79 -.15 -.08 .27 -.42 .15 -.50 .06 -.13

4 -.18 -.24 .44 -.49 -.31 .38 .19 .13 .07-.46 -.40 .67 -.40 -.08 .48 .42 -.02 -.21

Std Dev’s relative to overall means of Test and Reference Observationsafter correction for ‘tilt plane’ and ‘post effect’ and for levelcorrection ( -.67)

Drop TEST REFERENCE DIFF(T-R)No Mean S.D Mean S.D Mean S.D

1 .06 .44 -.06 .55 .11 .712 .05 .69 -.05 .58 .11 .903 -.44 .49 .44 .50 -.89 .714 -.67 .71 .67 .63 -1.34 .95

ALL -.25 .59 .25 .57 -.50 .82

Summary of combined results for all four drops

Mean Difference -.50Std Dev of Mean Difference .82

D-5

Blank Page

CONTRACT NO

ANNEX E

SHEET 1 OF 1

MAXIMUM

INITIAL

REDUCED

DEFECT CLASSIFICATION SHEET

BATCH SIZE: 25,000 INSPECTION LEVEL: II

BATCHES - NORMAL/INSP PREPARED BY: DGDQA/PS WPNS(A)

INSPECTION WILL NOT BE ALLOWED DATE : JANUARY 1988

STORE: COPPERS, CRUSHER, BALL FOR USE INGAUGES, CRUSHER, BALL MKS 8 & 9

COMPONENT . . . . . . . . . . . . . . . . . STORE BRANCH: DGLFS/QA/HY AMMB

CRITICAL DEFECTS MAJOR DEFECTS MINOR DEFECTSA=0.01

AQL : % DEFECTIVE AQL : % DEFECTIVE/DEFECTS 100 UNITS AQL: % DEFECTIVE/DEFECTS 100 UNITSB=0.1

FEATURE GAUGE CODE FEATURE GAUGE CODE FEATURE GAUGE CODENO NO NO NO NO NO

AQL ADIAMETER (AS PER PARA5.3 SECT 2)(MEASURE IN TWOMUTUALLY PERPENDICULARPLANES)

AQL A SAMPLE SIZE 1250AQL B ACCEPTANCE No 0MATERIAL COMPOSITION REJECT No 1(AS PER PARA 5.2 SECT 2)

AQL B SAMPLE SIZE 125ACCEPTANCE No 0REJECT No 1

Blank Page

DIRECTORATE OF STANDARDIZATIONMINISTRY OF DEFENCERoomKentigern House 65 Brown Street Glasgow G2 8EX

Telephone 041 248 7890ExtDirect Dialing 041-224-ExtTelex:

Your reference

Our Reference

D/D Stan/ 306/2/9Date

January 1991

INTERIM DEFENCE STANDARD IMPROVEMENT PROPOSAL

Defence Standard No: 13-36 (PART 8)/1

Title: CRUSHERS AND CRUSHER GAUGES

The above Defence Standard has been published as an INTERIM Standard and isprovisional because it has not been agreed by all authorities concerned with itsuse. It shall be applied to obtain information and experience on its applicationwhich will then permit the submission of observations and comments from users.

The purpose of this form therefore is to solicit any beneficial and constructivecomment that will assist the author and/or committee to review the INTERIMStandard prior to it being converted to a normal Standard.

Comments are to be entered below and any additional pertinent data which may alsobe of use in improving the Standard should be attached to this form and returnedto the Directorate of Standardization at the above address. No acknowledgementwill normally be sent.

NAME: J O MUIR S I GNATURE BRANCH: STAN 4C

1. Has any part of the Standard created problems or required interpretationduring use:

❑ ❑YES NO if ‘yes’ state,

a. clause number/s and wording:

b. recommendation for correcting the deficiencies:

2. Comments on any requirement considered too rigid:

Continued over

1DGDQA Form 0825

3. Is the Defence Standard restrictive:

❑ ❑YES NO (if ‘yes’ in what way)

4. General comment:

5. We agree that this INTERIM Standard (subject to amendments to take account ofour comments) when published in final form will cover our requirements.Should you find our comments at variance with the majority, we shall be gladof the opportunity to enlarge upon them before final publication.

Signature . . . . . . . . . . . . . . . . . . . . . . . . . . . . Representing . . . . . . . . . . . . . . . . . . . . . . .

Submitted by (print or type name and address): Telephone number:

Date:

Our Ref:

2

WP 38A


C Crown Copyright 1989

Published by and obtainable from:Ministry of DefenceDirectorate of StandardizationKentigern House65 Brown StreetGLASGOW G2 8EX

Tel No: 041-248 7890

The following Defence Standard file

This Standard may be fully reproducedexcept for sale purposes. Thefollowing conditions must be observed:

1 The Royal Coat of Arms and thepublishing imprint are to beomitted.

2 The following statement is to beinserted on the cover:‘Crown Copyright. Reprinted by(name of organization) with thepermission of Her Majesty’sStationery Office.’

Requests for commercial reproductionshould be addressed to MOD Stan 1,Kentigern House, 65 Brown Street,Glasgow G2 8EX

reference relates to the work on thisStandard - D/D Stan/306/2/9 (Stan 4c).

Contract Requirements

When Defence Standards are incorporated into contracts users areresponsible for their correct application and for complying with contractrequirements.

Revision of Defence Standards

Defence Standards are revised when necessary by the issue either ofamendments or of revised editions. It is important that users of DefenceStandards should ascertain that they are in possession of the latestamendments or editions. Information on all Defence Standards is containedin Def Stan 00-00 (Part 3) Section 4, Index of Standards for DefenceProcurement - Defence Standards Index published annually and supplementedperiodically by Standards in Defence News. Any person who, when making useof a Defence Standard encounters an inaccuracy or ambiguity is requested tonotify the Directorate of Standardization without delay in order that thematter may be investigated and appropriate action taken.

90/40075