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|NDT.net Issue - 2019-01 - NEWS |
Inspecting plastic toysPlastic toys are hot-ticket items during the holiday season. When shoppers are considering their purchases, safety and quality can play a role when deciding what to buy. Plastic toy manufacturers verify the quality of their products on the production line through spot checks and batch testing. The toys are also thoroughly inspected to ensure that they comply with international safety standards.
We’ve talked in the past about how XRF instruments can play a role in making toys safe, but did you know that some of our other instruments are used to help control toy quality? Toy manufacturers use instruments such as our 38DL PLUS® ultrasonic thickness gage to verify the wall thickness and uniformity of injection molded toys, which is an essential aspect of their overall quality and functionality.
Plastic ToysPlastic is one of the most common materials used to make modern toys. Plastic is such a popular manufacturing material because it’s durable—it can usually be bent and twisted without any serious damage. Plastic is also versatile. It can be molded and used in many different ways to create a huge variety of toys. Toys made from plastic also have some advantages. They last a long time, can stand up to the rigors of play, and are easy to clean.
Pieces of an injected molded toy—some assembly required
The Thick and Thin of Injection MoldingThe manufacturing process of certain toys—for example, building blocks and dress-up dolls—involves a technique called injection molding. Different types of plastic materials are injected in granular form into a precisely designed mold. The plastic is heated so it melts to a paste and lines the mold, and then it is cooled so it hardens. In the case of dolls, rotational casting, or roto-molding, is sometimes used to ensure that the plastic walls of the toys are uniform. Essentially, the mold is rotated slowly while heat is applied so the paste spreads evenly.
The raw plastic pellets used in injection molding
Manufacturing High-Quality Toys: More than Just Child’s PlayPrecision for the wall thickness of these parts is critical. If the dimensions exceed the established limits, flaws and damage can occur.
A toy’s wall thickness needs to comply with the tolerances set out in the design specs. For injection molded parts that are 1 to 20 mm thick, tolerances are as little as ±0.1 mm. Getting an accurate measurement on walls this thin was very challenging using older methods, such as cutting a sample part in half with a utility knife and measuring the thickness with a set of calipers.
How Thickness Gages Assist Quality AssuranceToy manufacturers can use a thickness gage to perform reliable, on-the-spot quality control. The 38DL PLUS thickness gage, for example, can measure the walls of plastic parts as thin as 0.8 mm. It can provide precision measurements of the wall thickness with a standard resolution of 0.01 mm (0.001 in.) for all transducers. And it can make the measurements from just one side of the part—no cutting required.
Ultrasonic thickness gages work by measuring the time it takes for an ultrasonic sound wave to travel through the plastic part. The sound wave travels from the transducer through the part until it bounces off the opposite surface to return to the transducer. The gage measures this transit time and, using the velocity of sound in the material being measured, calculates the thickness.
To meet the demands of the production floor, the 38DL PLUS thickness gage is compact, weighing only 0.814 kg (1.80 lb), and rugged, rated IP67 dustproof and waterproof, and equipped with a protective rubber boot. Post inspection, the GageView™ interface program enables users to transfer the thickness gage’s data to spreadsheet software and other PC programs for smooth quality-control reporting.
A plastic toy injection molding factory
SummaryGiven plastics’ durability, versatility of manufacturing, and relatively low cost, there’s no doubt that it will remain a popular material for making toys for many years to come. In addition to helping ensure that toys meet quality standards, thickness gages are also important for making plastic toys as green as possible. Using the minimal amount of material necessary to create a plastic toy is good for the environment, and thickness gages enable manufacturers to use minimal resources to create their products, helping ensure plastic toys remain on the shelves for many more holidays to come.
Tags: Thickness Gage, Quality Control, Plastic
Source: InSight Blog Olympus NDT Applications Team - December 11, 2018