How To Make Crosshatch Test On Plastic Sheet

The crosshatch test is a simple plastic engineering test to check coatings on a sample of plastics for stiffness, quality, and toughness.

In this guide, this test’s purpose is to prevent defects in your finished product within seconds and avoid a bad reputation in the marketplace.

Step-by-step Process How To Conduct Crosshatch Test On Plastic Sheet

Several steps involving the crosshatch test must be performed very carefully to achieve maximum efficiency in test results.

The steps are given as:

  1. Place the plastic sheet sample on the smooth surface for better support and enhanced cutting performance.
  2. Now place your cutter on the sheet in such a way that every cutting ed specimen must pierce into the plastic sheet at an equal depth.
  3. Elevate the top surface cutter handle to about 15° to ensure the cutter’s best attitude regarding this test.
  4. Ensuring all cutter tips penetration on the plastic sheet moves the assembly to about 1.9 cm-2.54 cm in a straight line.
  5. Now you need to repeat this process, but the cutter must make an angle of 90° to ensure it intersects the first cutting line.
  6. Now clean the surface with the separated flakes with a soft brush.
  7. Remove 7.5 cm of tape from the dispenser and apply it to the grid area with a plastic squeegee, pressing firmly.

Smooth down with your finger.

  1. Remove the tape after one minute by slowly and smoothly with 180° angle.
  2. After removal, the uniform color on the tape will indicate good contact with the plastic sheet.
  3. Now, repeat the test on two or three locations to obtain the average results.
  4. Now follow the references in the table to check the quality of your product by comparing the graphics.
ClassificationsRemoved Area %Crosscut Area Surface
5B0%
4B<5%
3B5-15%
2B15-35%
1B35-65%
0B>65%

How Crosshatch Testing For Plastic Compares To Other Adhesion Testing Procedures?

There are multiple testing procedures used to check the adhesion of materials.

The crosshatch test that we performed above presents the ASTM D3359 standard test method.

Pull-off Test

Another test is called pull-off adhesion, which follows the ASTM D4541 standard test method.

The specimen is glued on the adhesion surface and pulled off through the equipment in this method.

The tensile strength is checked and calculated through the software.

Bending Test

ASTM D4145 standard test is used for the adhesion flexibility of various materials.

In this test, coatings’ withstand ability can be found by applying stress to check the deformation analysis.

Bending platic

Bending plastic

When To Conducting Crosshatch Testing For Plastic Sheets Is Critical

Crosshatch testing is key to improving the quality of your plastic sheets and panels, but this method of determining adhesive strength only works for polypropylene films.

Therefore, you must conduct a crosshatch test before the film has been laminated .

This is to the core material for your composite, as the film needs to be in its original form before you can use adhesive tape and other materials to conduct the test.

Factors Influencing Efficiency Of Crosshatch Testing For Plastic Sheets

More importantly, the crosshatch test requires a skilled operator to perform; otherwise, some factors might disturb the efficiency of the results.

The two most important factors in this test that need to be considered are visual assessment and tape removal angle.

Peeling Angle

According to the standard, the peeling angle must be 180° as close as possible.

To ensure reproducibility of this test, the force required to remove the tape should be uniform, and the angle should be as per standard; otherwise, results might contradict other methods.

Visual Evaluation

It is hard to imagine visual assessment would fail for polymers that are not extremely transparent, but it can happen with crosshatch adhesion testing.

The wrong visual assessment may and often will result in misleading information.

As a result, this can lead to product quality issues such as low-end plastic parts, harmful material selection, and plastic product failure.

Advantages Of Crosshatch Testing For Plastic Sheets

There are multiple advantages of the crosshatch test for plastic sheets, but some of them are given as:

  1. Crosshatch testing is a great way to test the mechanical properties of different plastic sheets
  2. Crosshatch testing is the best method of evaluating adhesive strength in a plastic sheet.
  3. Especially for use in the automobile industry, these plastic sheets are subjected to rigorous mechanical testing to determine the quality or grade of plastic used.
  4. The crosshatch test is used to verify how different fast fluids penetrate a woven plastic sheet.
  5. Companies use this test to determine plastic as an alternative to glassware, metal cans, and other storage materials.
  6. This test is important when comparing various manufacturers and determining the best product for your application.

Limitations Of Crosshatch Testing For Plastic Sheets

There are some limitations as well despite many benefits of the crosshatch test, which are given as:

  • Crosshatch testing is an accurate predictor of a sheet’s initial bond strength; it is not an accurate indicator of the bond strength over time.

Most of the time, the sheet will lose approximately 50% of its initial bond strength in just one month.

Therefore, it is necessary to determine if your sheet loses any bond strength after 30 days and what type of loss your sheet will have experienced over time.

  • If your plastic parts are not separated, the crosshatch test may yield poor results.
  • This test can’t be used to measure slip resistance or shear strength directly.
  • The types of plastic and thickness can also make a difference in your results, so this test is unsuitable for all thicknesses.
  • It could be argued that any small variances in the standard cutting angle will lead to premature failures of very brittle adhesives.

Safety Consideration During Crosshatch Testing For Plastic Sheets

The safety concerns associated with the crosshatch test are given as:

  • Ensuring safety during sharp-cutting methods such as crosshatch testing requires that the operator uses cutting tools that are safe to handle and not likely to puncture while in use.
  • If a person does not have tweezers, he should place rubber sections on the grid to perform the crosshatch test.
  • Always use personal protective equipment (PPE) while performing the test.
  • Suppose you are testing a PVC material known to release hydrochloric acid as gas as it burns.

In that case, you should be wearing a respirator and safety glasses when conducting further tests on the material.

  • There is a chemical reaction between test chemicals used during crosshatching and common plastics found in laboratory environments (e.g., natural rubber gloves).
  • Washing hands and other exposed skin areas immediately after removing solvent-contaminated gloves.
  • Before operating any testing instruments, read and follow the specific safety instructions from the equipment manufacturer.

Equipment You Need For Crosshatch Testing For Plastic Sheets

Crosshatch testing kit

Crossshatch testing kit

The crosshatch test is very simple and requires less equipment.

For Crosshatch testing for plastic sheets, the equipment you will need are:

  • Cross-Hatch Cutter (Manual or Automatic)
  • Adhesion Test Tape
  • Magnifier

Classifications Available For Crosshatch Testing For Plastic Sheets

The “Crosshatch” test is a universal reference for the durability of plastic sheets.

A crosshatch pattern provides a general indication of the sheet’s tear-resistance and “abrasion resistance.”

The various classifications based on pictures given above in the table are described as:

i. The square edges of the cuts are perfectly smooth, and there is no chipping or cracking, classified as 5B.

ii. There are small flakes of the coating found at the intersections of the cuts. These flakes are smaller than 5% of an area and do not affect performance. This chip can be classed as BS/ISO/DIN class 1 ASTM class 4B.

iii. A cross-cut area that is greater than 5% but not greater than 15% is affected is classified as class 3B.

iv. Flaking has occurred along the edges of the cuts, with parts shedding up to 15-35% of their coating classified as 2B.

v. Few cuts in the coating have detached, with significantly less than a 1/3rd or 35-65% of the surface area damaged is classified as 1B.

vi. At this point, any degree of flaking cannot be classified.

Methods Of Crosshatch Testing For Plastic Sheets

There are several methods of crosshatch used for plastic sheets; some of them are given as:

i. Pull off Adhesion Test

ii. Knife Test

iii. Tape Test

iv. Scrape Test

v. Bending Test

How To Ensure Crosshatch Testing For Plastic Sheets Precision And Accuracy

Crosshatch testing for plastic sheets isn’t only a practical and reliable means of evaluation.

It has also been attested to be one of the best standards to know if there are any defective products left to release.

Crosshatch testing involves scratching the polymer surface with a sharp tool to make a matrix of lines.

Which then it is  filled with fine particles and rubbed with standardized clothes.

A provider of testing equipment and consumables, such as knives and blades, can help ensure precision and accuracy concerning your crosshatch test results.

Parameters Crosshatch Testing For Plastic Sheets For Plastic Investigate

There are various parameters in crosshatch testing for plastic sheets, which are described as:

i. The angle of the cuts is used to categorize the force required to remove the adhesive layer, as shown in the table below.

ii. This test involves cutting a sample multiple times with a sharp blade to make small intersecting cuts across the sample’s surface.

iii. The tape removal angle is an important parameter for achieving highly efficient test results.

At WeProFab, we adhere to strict quality testing and validation.

We strive to ensure that our plastic materials comply and pass the crosshatch test.

WeProFab will share the test report upon request.

For questions or inquiry, contact us now.

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