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Tubular Impact Tester 304

Tubular Impact Tester 304
Tubular Impact Tester 304
Product Code : 304
Brand Name : ERICHSEN
Product Description

ERICHSEN TUBULAR IMPACT TESTER 304
 
Principle of Variable Height Impact Test
Surface coatings are frequently subjected to impacts which deform the base material, thus placing stress on the adhesion and cohesion of the coating. The ball impact test simulates this type of stress under standardised conditions. A ball punch of defined weight the bottom of which is of fixed diameter, is dropped freely down a guide tube from an agreed or variable height.After the impact, the deformed zone of the specimen surface is examined for cracks and flaking. The ball impact test is comparable to a dynamic version of the ERICHSEN Cupping Test.

Standards for Impact Tests
Mechanically the test instruments described in the various standards for impact tests are almost identical. The important differences effect only the
diameter of the punch end,
inside diameter of the die,
mass of the falling weight,
scale for the dropping height/energy,
clamping sleeves and stops to limit the indentation depth.
 
In the following table these instrument parameters are summarised and the versions of the ERICHSEN Variable Height Impact Tester, Model 304, are shown in relation to the different impact test standards.
Model 304-AFNOR incorporates a special feature not included in the other versions: The bore in the die is less than the diameter of the spherical end of the falling weight. As a result the depth reached is limited to a maximum that will vary depending on the specimen thickness.
 
The conditions are similar in the case of the SNV version: Here the two diameters are equal.It should be noted that the 400 g weight which is actually required for the AFNOR version to comply with the standard, is not included in the basic equipment of Model 304-AFNOR, since most users only employ the 1000 g falling weight.
 
The versions for ISO, DIN and ASTM standards are available from our standard production programme,
but the Models 304-ECCA, 304-AFNOR and 304-SNV are produced only on demand. In principle other versions of impact testers with different falling weight, ball and die geometries can be supplied as mutually agreed.

Standard

Ball Dia

Die I.D

Falling Weight

Scale/Division

ERICHSEN

Model

 

Status

 

ISO 6272

(DIN 55 669)*

ECCA T5-1995

EN 13523-5 ***

20mm

27mm

1 + 1 kg **

 

1000/5 mm

 

304-ISO

304-DIN

 

Standard

 

 

 

 

 

Version

ASTM D 2794

5/8“(15,9 mm)

0.64“(16.3 mm)

2 pounds (0.9 kg)

80/2 inch pounds

304-ASTM

ECCA T5-1985

ECCA T6-1985

ASTM D 3029

(Method Gc)

 

5/8“(15.9 mm)

 

0.64“(16.3 mm)

2 + 2 pounds **

(0.9 + 0.9 kg)

 

 

80/2 inch pounds

And

160/4 inch pounds

 

 

304-ECCA

 

Special

version

(upon

 

NF T 30-017

23 mm

22 mm

1 kg

1000/5 mm

304-AFNOR request)

 

SNV 37109

½“(12.7 mm)

1/2“(12.7 mm)

2 pounds (0.9 kg)

1000/5 mm

304-SNV

 

 
*   Corresponds to ISO 6272, but without clamping sleeves and stops to limit the
     indentation depth of the falling weight.
** The basic weight is doubled by bolting on a supplementary weight.
*** Corresponds to ECCA T5-1995
 
 
Model 304 - General Description
The Impact Tester, Model 304, in all its variations, consists of a sturdy base plate with attached holding arm into which the slotted fall tube is clamped (transverse thread screw). In the ISO and DIN versions the screw is tightened with a clamping lever enabling the apparatus to be set quickly for different specimen thicknesses. The lever can also be pulled out a short way against a spring force. It is thus disengaged and can be turned freely.
 
Below the falling tube and carried in the base plate is mounted the die in accordance with the relevant standard. The die is easily exchangeable but at the same time is accurately fitted so that the centre lines of guide tube and die coincide.
 
At the bottom end of the falling weight is the ball punch appropriate to the die being used and this has on its side a protruding pin which is guided in the slot along the length of the tube and is used to lift the weight to the desired height. On the ISO, DIN and ECCA versions the mass of the falling weight can be doubled by bolting on an additional weight.
 
Scales are mounted along the slot which in the case of instruments for ISO, DIN, AFNOR and SNV standards are calibrated in „cm“ or for ASTM instruments in „inch lbs“. In the case of the ECCA version there are two different inch lbs scales on either side of the slot.
 
According to the standard the Model 304-ISO is equipped with a clamping sleeve to hold the test panel in position and with stops of different thicknesses to limit the indentation depth of the falling weight. In addition the Models 304-ISO and 304-DIN have a further special feature, namely a movable ring over the falling tube. The ring is guided in the slot and clamped by means of a knurled screw and serves as stop for the pin protruding from the side of the falling weight. This arrangement provides for accurate presetting of the potential energy which is a considerable convenience when performing tests starting from a fixed height.
 
Evaluation and Interpretation
The specimens deformed by the ball impact are normally examined for cracks and peeling visually perhaps with the aid of a magnifying glass. To ensure that less obvious cracks will still be identified, the ASTM D 2794 standard suggests two more sensitive methods of examination:
Application to the specimen of copper sulphate solution to enable the smallest faults
   in the  coating to be shown up in clear contrast. This procedure is only effective, if the    base material is steel and if any anti-corrosion coating such as phosphating has also        broken through as a result  of the impact.
In the case of electrically insulating coatings applied on a metallic base, the test area      can also be examined with a porosity test instrument. For this, simple conductivity          testers using a 9 VDC supply and a dampened sponge as test probe are all that is            required. The impact energy is expressed in different terms in the individual standards. In ISO, DIN, NF and SNV the dropping height (in mm) in conjunction with the weight of the impact body is used for a relative energy scale. The remaining impact  test standards lay down the use of absolute units of energy: kg m (ISO 6272, ASTM D 2794),
  Joule (ASTM D 3029, ECCA T5), inch lbs (ASTM D 2794 and ASTM D 3029).
 
These units of energy relate to one another as follows:
 
1 J(oule) = 0.1 kg m = 8.8 inch lbs
 
The conversion factors can be used to compare the energy values that can be set on the various versions of the instrument. Because of the differing ball and die dimensions, it is, however, not possible to convert results obtained with the different ball impact test methods by any method of accurate calculation.
The test in accordance with ECCA T6 takes up a special position. In this case a coating previously damaged by cross cutting is subjected to convex deformation („reverse impact“) and the extent of the damage is expressed as a percentage on the basis of the peeled area.
 
 


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