Barcol hardness test

13 Surface quality tests 23.11.13.1 Barcol hardness test 

The Barcol hardness test is a good indication of cure. Barcol readings will vary with different resin systems for example, the more resilient resins will normally give lower Barcol readings. The US Department of Commerce Product Standard PS-15-69 and ASTM D3299 indicate that readings should be specified at 90% of the manufacturer s recommendation for a particular cast resin. 

Laminates containing thixotropic agents and/or antimony trioxide have readings 3-5 units higher. Use of paraffin, synthetic fibre overlays, or an unreinforced gel coat may reduce the Barcol reading by 3-10 units. 

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It is important when conducting expensive test programmes that the constituents be checked for quality prior to use and that the fabricated materials be checked after manufacture, or on receipt if already fabricated. The techniques used vary from the Barcol hardness test (see below) to the more rigorous DMA (dynamic mechanical analysis ISO 6721 (ten parts) [14]) or DSC [differential scanning calorimetry ISO 11,357 (7 parts) [15]) test methods. There is some concern that these tests do not give the same values due to subtle variations between different manufacturers equipment. 

The simple and nondestructive Barcol hardness test has the added advantage that it can be conducted in situ on the factory floor (see Section 6). The other techniques are more costly, require a greater degree of operator training, and are not practical for in situ factory use. However, they are suitable for checking incoming material as preimpregnates or laminates. 

The only specialist use of hardness testing for composite materials is related to the assessment of cure using the Barcol hardness test available as EN 59 [16], The test is frequently used as a low-cost quality check on the cure of laminates such as hand layup CSM materials used in marine and general purpose commercial moldings. Care should be taken to avoid cracking thin laminates. 

This decay rate is nearly equivalent to that exhibited by one g of radium in equilibrium with its disintegration products. A miUicurie (mCi) is 0.001 curie, curie point See magnetized curie point, curing See autoclave nitrogen atmosphere cure extruder wire and cable process, dry cure inhibitor prepreg volatile content reinforced plastic resin transfer molding test, Barcol hardness test, scorch Mooney thermoset plastic vulcanization welding, induction. 

ASTM D2583 specihes the Barcol hardness test. The hardness value can be used as a measure of the degree of cure of a plastic material. Barcol hardness is generally measured for rigid plastics, particularly reinforced thermosetting resins. The usual range is about 50B-90B. Barcol 60B is equivalent to Shore SOD and to Rockwell MIOO. 

Not all air-inhibited surfaces can be detected by the Barcol hardness tests. It is recommended that the acetone sensitivity test should also be used, where appropriate. This involves application of a small amount of acetone to the resin surface. The wetted surface is then rubbed lightly with the finger until the acetone has evaporated. If the surface softens or becomes tacky, the resin has not fully cured. 

The Barcol hardness test was devised mainly for measuring hardness of both reinforced and nonreinforced rigid plastics. The tester is a portable instrument that can be carried around to measure hardness of fabricated parts as well as the test specimens. 

Barcol hardness tests consist of an indentor with a sharp, conical tip and indicating device in the form of a dial with 100 divisions. Each division represents a depth of 0.0003-in. penetration. The test specimens are required to be of 1/16-in. minimum thickness. 

Test Method for Indentation Hardness of Rigid Plastics via Barcol Impresser Test Method for Indentation Hardness of Metal using Portable Hardness Testers Webster Hardness Gauge ... 

Barcol Indenter. The Barcol hardness tester is a hand-held, spring-loaded instmment with a steel indenter developed for use on hard plastics and soft metals (ASTM D2583) (2). In use the indenter is forced into the sample surface and a hardness number is read direcdy off the integral dial indicator caUbrated on a 0 to 100 scale. Barcol hardness numbers do not relate to nor can they be converted to other hardness scales. The Barcol instmment is caUbrated at each use by indenting an aluminum ahoy standard disk suppHed with it. The Barcol test is relatively insensitive to surface condition but may be affected by test sample size and thickness. 

Vickers and Knoop indentors, Barcol hardness, and Shore durometers (2) (b) to measure the resistance of a material to scratching by another material or by a sharp point, such as the Bierbaum hardness or scratch-resistance test and the Moh one for hardness and (c) to measure rebound efficiency or resilience, such as the various Rockwell hardness tests. The various tests provide different behavior characteristics for plastics, as described by different ASTM standards such as D 785. The ASTM and other sources provide different degrees of comparison for some of these tests. 

Barcol hardness Also called Barcol impresses It is a measure of the hardness of a plastic, that includes laminate or reinforced plastic, using a Barber Coleman spring loaded indenter. Gives a direct reading on a 0 to 100 scale higher number indicates greater hardness. This test is often used to measure the degree of cure for plastics, particularly TS plastics. 

The shore durometer is a simple instrument used to measure the resistance of a material to the penetration of a blunt needle. In the Barcol approach, a sharp indentor is used to measure the ability of a sample to resist penetration by the indentor (Figure 14.18). The values given in Table 14.3 are for one specific set of conditions and needle area for the Barcol and Brinell hardness tests. 

Other hardness tests that are sometimes applied to plastics include Barcol, Brincll. and Vickers, The former is normally applied to composites and is described more fully in Chapter 18. Brincll and Vickers are not standardized for pla.stics. being designed for metals, although values for plastics using these scales can be found in the literature. The Brincll method is standardized for use with metals in ISO 6506 [12], BS EN 10003 [1.3], and ASTM ElO [14],... 

Barcol hardness See test, Barcol hardness, bare glass See fiberglass, bare. 

The resistance to compression and surface indentation, usually measured by the depth of penetration of a blunt point under a given load using a particular instrument according to a prescribed procedure. Among the most important methods of testing are Barcol hardness, Brinell hardness, Knoop hardness, Mohs hardness, Rockwell hardness, and Shore hardness. 

Barcol hardness n. The resistance of a material to penetration by a sharp steel point under a known load with an instrument called the Barcol Impressor. Direct readings are obtained on a scale from 0 to 100. The instrument has often been used as a way of judging the degree of cure of thermosetting resins and harder materials. The ASTM test, www.astm.org, is referred to as Indentation Hardness of Rigid Plastics . 

Using your fingernail is a satisfactory way of determing hardness. If desired a Barcol impressor, or a pencil hardness test may be employed. 

Several pultmsion companies use Barcol hardness testers to assess the degree of cure of the produced parts. This enables the tracing of products with insufficient degree of cure of the resin matrix, which leads to lower mechanical performance. The quality control of pultruded produced parts can also include other mechanical characterisation tests which can sometimes be carried out in the laboratory facilities of pultrusion companies. EN 13706-3 (CEN, 2002) defines two grades of FRP pultruded profiles, specifying minimum values for material properties and the relevant test methods. The requirements for certain applications (e.g. petroleum and natural gas industries) can be stricter and often include aspects related to fire reaction and fire resistance behaviour, e.g. NBR 15708-1 (ABNT, 2011). 

The test is carried out by placing the indentor onto the specimen and applying uniform pressure against the instrument. The pressure is applied until the dial indication reaches maximum. The depth of penetration is automatically converted to a hardness reading in absolute Barcol numbers. When measuring the Barcol hardness of the reinforced plastic material, the variation in hardness reading caused by the difference in hardness between resin and filler materials should be taken into account. 

A UV-cured polyester matrix reinforced with glass fibers was tested on both exposed and non-exposed sides in order to establish the relationship between irradiation parameters and surface Barcol hardness [11]. The difference between sides increased along with the distance between irradiation source and laminates. 

This test method provides for the determination of changes in the physical properties of the test panel and test media during and after the one-side exposure in the test media. Determination of changes include Barcol hardness, appearance of panel, appearance of test media, flexural properties, and thickness. 

As with metals, hardness represents a material s resistanee to seratehing, penetration, marring, and so on. Polymers are softer than metals and eeramies, and most hardness tests are condncted by penetration teehniques similar to those deseribed for metals in Section 6.10. Rockwell tests are frequently used for polymers. Other indentation techniques employed are the Durometer and Barcol. ... 

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