In-mold thickness gauges for blow molders.

In-Mold Thickness Gauges for Blow Molders

Probably the first NPE display of in-mold thickness measuring for blow molders was seen in Chicago this past June at related exhibits by Inoex Theysohn, a German instrument maker with offices in McPherson, Kan. (Inoex div. of American Maplan), and Hobson Bros. Aluminum Foundry and Mould Works Inc. in Shell Rock, Iowa.

An ultrasonic thickness gauge calculates part thickness by timing a sound wave emitted from a sensor in the mold wall through the material and back, then calibrating it against a mechanically measured part sample. A handful of European molders are said to use it, mostly for auto fuel tank SPC, but it's not thought to be in commercial use yet here.

Hobson displayed a mold for a 10 x 54-in. tank with four Inoex sensors at critical points. Inoex's new USS-IMM (ultrasonic system for in-mold measuring) reads thickness from up to 32 sensors attached to an IBM AT-computer with custom software. Sensor measuring range is 0.08-0.3 in. with 0.0004-in. resolution, including the ability to evaluate coex layers, Inoex says. The system was also displayed at Inoex's booth.

In June, Hobson and Inoex got together by chance when their respective presidents met traveling in Mexico. Only weeks before NPE, Hobson became Inoex's U.S. sales representative for the in-mold system and built its first thickness-measuring mold, says Hobson sales manager Herb Lease.

An eight-channel USS-IMM with sensors, AT-compatible computer, 14-in. monitor and printer costs about $38,000. Existing molds can be adapted to hold the 0.4 in. diam. x 1.4 in. long sensors. Hobson is working to get the device to feed data into Barber-Colman's MACO 8000 parison-thickness program to give molders "control of wall thickness presently unattainable," Lease says. (CIRCLE 13)

ANOTHER ONE ON THE WAY

Panametrics Inc. in Waltham, Mass., discussed its new In-Mold Ultrasonic Thickness Measurement System at NPE, but didn't display it. Model 5215 is a multiplexed, ultrasonic thickness gauge available in one-, four-, and eight-channel versions with custom models up to 40 channels. It uses custom software to process and store thickness data and needs an IBM-compatible computer. The 5215's measurement range is 0.04-0.30 in. with 0.001-in. resolution and typical accuracy of [+ or -] 0.004 in., depending on temperature and plastic density, Panametrics says. Sales engineer Steve LaBreck says the 5215 gauge itself isn't new, but the in-mold application and related software is. A four-channel in-mold 5215 with transducers but without computer starts around $16,000. (CIRCLE 14)

PHOTO : At NPE, Hobson Bros. displayed a tank liner mold built with Inoex's new USS-IMM ultrasonic thickness-measuring system, which measures wall thickness from up to 32 sensors inside the mold. It can measure coex layers, too.