Abstract: A magnetic thickness gauge is disclosed wherein a balance arm is pivotably mounted in a housing with a spring providing a bias force to counteract a magnetic attraction of the balance arm toward a base of a coating to be measured. The balance arm is provided with a probe assembly including a magnet selectively positionable with respect to a spherical contact member of either a particular alloy of aluminum, iron and silicon or of tungsten carbide. The housing is preferably provided with supports at either end of the gauge. A balance arm is moved by way of a protrusion provided between the probe assembly and an adjustment knob for the spring with a scale and pointer indicating the thickness of the coating to be measured.

Abstract: A system for measuring the cladding thickness on aluminum sheets which includes a cylindrical probe holder with four evenly spaced contact points surrounding a low temperature coefficient torroidal ferrite core which provides a signal to an aluminum cladding thickness signal processing circuit comprising a crystal oscillator, low drift detector, and push button calibration instrument portion thereby enabling drift free repeatable measurements.

Abstract: A conductive film deposition rate monitoring method for measuring the real time deposition rate of a metallic deposition process particularly an electroless plating bath, including the steps of positioning an eddy current detector within a predetermined distance of a test surface where the deposition is to be deposited, and the step of monitoring the output of the detector. The apparatus comprises an eddy current sensor and a non-metallic housing for the sensor, having a non-conductive wall of predetermined thickness between the sensor and the surface of the wall distant from the sensor, the distant wall being immersed in the deposition environment, such as a plating bath, so that a deposit takes place on the distant surface, and measuring means connected to the output of the sensor for measuring the amplitude and rate of change of the output of the sensor.

Abstract: An eddy current thickness probe for measuring the thickness of a weakly ferromagnetic material layer on a ferromagnetic base is provided with an essentially constant magnetic field bias. The magnetic field bias is of sufficient strength to substantially saturate ferromagnetic constituents in the weakly ferromagnetic layer. This eliminates any effects of changes in permeability of the weakly ferromagnetic layer which would otherwise impair the operation of an eddy current thickness gauge.

Abstract: A system (10) for determining the thickness of a magnetic flux conductive clad material over a magnetic flux conductive base material of different permeability applies on alternating voltage (96) to the primary winding (52) of an incomplete core-type transformer (54). The secondary winding (40) voltage to primary winding (52) voltage ratio is determined with the material being clad-thickness measured (56) completing the incomplete core (54). The voltage ratio is a nondestructive measurement of the thickness (64) of the clad material. The preferred embodiment applies a constant voltage alternating voltage power source (18) to the primary winding (52). This obviates the need to determine the ratio of voltages. The secondary winding (40) voltage is a direct nondestructive measurement of the thickness (64) of the clad material.

Abstract: An instrument for measurement of thickness of a non-magnetic layer on a magnetic or magnetizeable substrate including a permanent magnet having a test pole which is resting against the non-magnetic layer and an opposite pole, a comparison body arranged at a distance from the opposite pole, a mechanism for adjusting the spacing of the comparison body from the opposite pole until the magnetic fields between the comparison body and the opposite pole and between the substrate and the test plate are equal and a device for displaying such spacing. In this manner, the gap between the comparison body and the opposite pole of the magnet becomes the same as the spacing between the test pole and the substrate which is the thickness of the non-magnetic layer. Different embodiments are presented. In three of the embodiments, when the magnetic fields become equal at both poles of the magnet, the magnet moves away from the non-magnetic substrate.

Abstract: A coating thickness and surface comparator for measuring the thickness of nonmagnetic coatings (28) or roughness on ferromagnetic base materials. A permanent rod magnet (6) and a ferromagnetic rod (16) are supported by nonmagnetic slides (12, 14) parallel to one another. When a standard base (24) is placed at one end (22) of the rod magnet (6) and a coated or roughened base (30) is placed at the other end, the slides (12, 14) are pushed together toward the middle of the rod magnet (6). The coincidence of the slides (12, 14) varies from the middle of the bar magnet (6) in proportion to coating thickness (28) or roughness.

Abstract: A film thickness gauge for measuring the thickness of paint, etc. has a magnet which is placed on the surface to be attracted by a magnetic substrate. The magnet is withdrawn by spring tension. A withdrawal member is braked when the magnet is released and the position of the withdrawal member on release is indicated in terms of the thickness of the coating.

Abstract: A layer-thickness meter for measuring the thickness of a non-magnetic layer upon a ferromagnetic substrate wherein the force required to raise from the layer to be measured a permanent magnet carried in a balanced lever arm is measured by means of a spring and taken as a measure of the layer thickness, the spring being stressed by rotation of a scale disc graduated in terms of layer thickness and co-operating with an index mark upon a housing of the meter, the circumferential edge of said disc being serrated or indented for engagement by a pawl so as to lock the disc in response to detachment of the permanent magnet from the layer surface, said pawl comprising a pivotally mounted bearing plate from which project two rigid stops which between them loosely embrace said lever arm at a location along said arm such that the pawl is actuated through one said stop to disengage from the disc edge when said permanent magnet is in contact with said layer surface and actuated through the other said stop to engage and lo

Abstract: Instrument for measuring thickness of coatings on substrate based on space-dependent, electromagnetic interaction between a measuring probe resting against the coating and the substrate comprising a compensating probe, a comparison body with properties similar to that of the substrate, a mechanism for adjusting the spacing of the compensating probe from the comparison body, until the same electromagnetic interaction is obtained as for the measuring probe and the substrate and a device for displaying the spacing between the compensating probe and comparison body.

Abstract: A coating thickness gauge employs a permanent magnet suspended on a coil spring within a pencil shaped housing; the spring being attached to a slide which encircles the housing aid is manually slidable along the length of the housing to adjust the tension of the spring exerted on the magnet. The end of the magnet projects through the end of the housing in contact with a coating deposited on a ferromagnetic base so that the thickness of the coating is measured in terms of the spring tension exerted when the side is moved to pull the magnet away from the coating and this thickness can be read on a scale mounted along the length of the housing. The slide can be provided with internal resilient friction rings or an internal expandable friction element can be placed in the housing to resist inadvertent movement of the slide and an internal stop can be employed to prevent bouncing of the magnet to displace the slide.

Abstract: A magnetic brush developing system for electrostatic duplication uses a developer having a magnetic carrier and non-magnetic toner which is transferred by the brush to an electrostatic image. A analog signal is derived using a Hall sensor in contact with the brush and adjacent to a magnet of the brush. The location of the sensor after and downstream of the transfer point provides information in the signal both as to the absolute value of the concentration (ratio of toner to carrier by weight) as well as the rate of transfer of the toner to the electrostatic image. These signals are used to control the supplying of replenishment toner to the developer only when the concentration of toner drops below a predetermined desired value and then at a rate commensurate with the rate of transfer of toner to the electrostatic image.

Abstract: An apparatus for gauging the thickness of coatings on metal products, whose casing accommodates: a wheel system; a spring actuator having a means for its being wound up, said actuator being connected to one of the members of said wheel system for said system to rotate; two balanced levers the first one of which carries a gauging permanent magnet adapted to interact with a ferromagnetic coating of the product being gauged or with the base thereof in case of a non-magnetic coating while the second lever is adapted to interact with said first balanced lever in cases where the break away force of the first balanced lever is not high enough to break-away said gauging permanent magnet from the product being gauged; two coiled springs of which one spring is connected, to said first balanced arm, and to one of the shafts of said wheel system, whereas the other coiled spring is connected, to said second balanced lever, and to said casing in such a manner as to adjust the spring tension; a magnetic element attached to

Abstract: An apparatus for gauging the thickness of coatings on metal products comprises a casing which accommodates a wheel system; a spring actuator with a mechanism for its winding, the actuator being linked to the wheel system so as to enable its rotation; two levers independently balanced in a static state the first of which carries a permanent magnet interacting through its field with a ferromagnetic coating on a product or with the base thereof in case of a nonmagnetic coating, the second of the two levers interacting with the first lever in the event when its force necessary to break away the permanent magnet from the product being gauged is insufficient; two coiled springs, the first of which is connected through one end thereof with the first lever and through the other end with one of the shafts of the wheel system, the second of the two coiled springs being connected through one of its ends with the second lever and through the other end thereof with a spring tensioning control mechanism.

Abstract: An improvement is provided in a device for measuring the thickness of non-magnetic layers on magnetic substrates by determining the adhesion of a magnet in contact with the layer. The device comprises a housing, a scale balance carrying the magnet at one end thereof, the scale balance being mounted rotatably on an axis, a manually rotatable disk and a first spring means connected to the scale balance at one end and to the scale disk at the other end. The scale disk and first spiral spring are coaxial with the scale balance axis. The improvement comprises drive means including a second spiral spring means which has one end attached to the casing and the other end attached to the scale disk. The second spiral spring is coaxial with the scale balance axis. The spring tension of the second spiral spring means is slightly greater than that of the first spiral spring means and counteracts the first spiral spring means.

Abstract: The calibration of magnetic gauges used for measuring the thickness of a layer applied to a base can be accomplished by the use of a test sheet composed of an essentially uncoated material which exerts a lesser influence on the gauge for a given thickness than the material comprising the base upon which the measured layer is applied. An uncoated test sheet of a certain thickness, when brought into contact with the pole piece of a thickness gauge, will produce a reading equivalent to that produced when the gauge measures a layer of predetermined thickness applied to the usual base material. For calibrating a gauge used to measure the thickness of a non-magnetic layer on a ferromagnetic base, the test sheet may be a material of less magnetic conductivity, permeability and/or saturation than that of the usual base material. A non-limitative example of a material suitable for use as a test sheet is pure nickel.

Abstract: A magnetic thickness gauge having a rotatable indicator dial which is rotated to lift a permanent magnet by means of a tension spring, from the surface being measured, is provided with an automatic brake which locks the dial in place as soon as the magnet is pulled away.

Abstract: A thickness gauge for measuring the thickness of a layer applied to a ferromagnetic base by measuring the attractive force of a permanent magnet in contact with the applied layer is provided with easily removable, interchangeable scales to permit direct reading of thickness in terms of metric, English or other units, or in accordance with the characteristics of the particular magnet used in the gauge.