Profilometers

Profilometer – This is a special device for measuring the surface roughness of individual parts, mechanisms and elements made from materials of various density. It helps to determine the product quality and the need for its additional processing. Use, and especially the choice of the device are important stages of almost any production process. Therefore, before purchasing and proceeding with the meter, it is necessary to study in detail what kinds of profilometers, their functionality and technological features.

What it is?

Surface roughness indicator – This is one of the main technical characteristics of the quality of a product designed to work in harsh conditions that suggest strong wear of manufacturing material. From the level of roughness will be depended on both the overall quality of the work of products – its operational parameters and the duration of use. The roughness indicator is very important, for example, for internal combustion engines, other similar nodes and mechanisms with a large number of moving parts and elements.

During operation, continuous processes that have a negative impact on the structure and integrity of the material occur on the working surfaces of such mechanisms

  • the formation of chips, cracks and burrs of various sizes;

  • Mechanical wear of the material;

  • Metal erosion, partial crumpled.

Increase the technical and operational characteristics of the product, improve the quality of its work, as well as extend the shelf life significantly helps additional technological processing – Grinding. It will depend on it the level of surface roughness, which is measured by a profilometry.

Similar arising defects can have even greater influence on the quality of the work of the mechanism, and, accordingly, rapidly cause its deformation. Yes, and the overheating of the metal most often occurs due to excessive friction, the reason for which the excessive roughness of the surface of the individual element becomes.

Therefore, it is roughness that significantly affects such technical indicators of materials as:

  • resistance to corrosion formation;

  • total wear resistance;

  • Permissible coefficient of friction.

This device allows you to determine the exact condition of the material surface, and most importantly, the need for its further processing (stripping or grinding).

Views

According to the principle of operation, the profilometrs are divided into Contact and Contact Devices. Contact devices are equipped with a special steel dipstick with a solid tip. It determines the level of roughness by moving on the surface of the product, and gives indicators to the screen installed in the device body.

Contactless or optical profilometers determine the level of roughness of the part using an optical sensor and a laser, which also exploring the surface, displays the received data to a special miniature monitor. Let us consider in more detail both varieties of profilometers, the features of their work and the main technical characteristics.

Contribute profilometrs

For a visual example, consider one of the most common contact profile – the device with digital reading 296 models. It is a typical representative of the devices in this class of measuring equipment, the work of which is based on an inductive signal conversion. This meter is designed to determine the level of roughness of only flat surfaces. Structurally, the contact profilometer consists of such elements:

  • steel probe with solid, as a rule, with a diamond tip;

  • Device to move the probe;

  • roughness converter;

  • digital converter and electric power amplifier;

  • display or miniature monitor;

  • reverse sensors to control the diploma, direction of its movement;

  • Measurement mode switch;

  • Temporary interval installation relay.

Profilometer model 296, as well as devices of such a modification, for example, a profilometer of 130 models, are considered stationary measuring equipment. These devices are mainly used to determine the roughness of surfaces only in laboratory, workshop conditions.

But, besides them, there are also mobile or portable contact profile profilometers having small dimensions. For example, the measuring device of the Russian production of the TR-100 model with a piezoelectric converter.

Despite the fact that this profilometer works on the same principle as the previous models, its functionality allows to determine the level of roughness not only on flat, but also on convex and concave surfaces.

Adjust the output values ​​or indication in TR-100 models It is carried out at the expense of a special node, further built into the main working circuit of the device. In addition, the TR-100 profilometer has a wider range of measurement – from 0.05 to 50 micrometers (microns). Its essential minus compared to laboratory or shop vehicles – lower definition accuracy (the difference between models is about 10-12%).

Contactless profilometrs

Unlike contact models, contactless profilometrs have wider opportunities. Therefore, today they got much more distribution, more often used in production. Their main advantages are the possibility of remote scanning, as well as the function of the operational data transmission and automatic output of the computer monitor or the printer for subsequent printout. The permissible remoteness or distance from the surface under study will depend on the specific model of the meter. As in the case of contact models, contactless devices also have two main species – stationary and portable.

The contactless stationary profilometer with the function of recording the result obtained includes such items:

  • Planting plate with special grooves in which the material or product is recorded;

  • Special laser head for scanning surface;

  • Optical device with primary measuring transducers – a special sensor or sensor;

  • The guide channel for wave transmission is a waveguide;

  • Computerized node with the appropriate user interface for controlling the instrument and connecting additional recording devices to it.

The thoughtful functionality of the contactless optical profilometer allows you to determine and display the monitor is very large, and in most cases the comprehensive amount of the necessary information. Detailed data helps as accurately as possible to set the level of surface roughness and the need for its further processing. The information obtained includes such important indicators as:

  • Scanning site profile – longitudinal and transverse;

  • The maximum permissible accuracy of measuring a particular surface;

  • Discreteness (intermittentness) of the instrument measuring step;

  • counting accuracy at the time of scanning, as well as a possible total total error.

In addition to the main functional, in such profilometers there is an opportunity Record the results obtained on a special thermal print paper. The recording itself is executed as a profilogram, so that the device can also be used as a full profilograph. Manage and scan control is carried out in a separate dialogue mode, it allows you to re-measure the roughness level not for all the product, but only on the necessary sections.

As an example of a portable or mobile contactless profilometer, we consider one of the most popular models of this type of device – German MAHR MARSURF PS1 meter. In this compact device, the control signal is transmitted to the appropriate scheme using a special optical sensor. The random involuntary fluctuations (periodic partial changes) of the distance between the surface under study and the reader of the device are compensated due to the automatic measurement steps calibration system.

The profilometer is equipped with a convenient digital display and a special retractable stylus of contactless action. Range of measuring the level of roughness in Portable model Mahr Marsurf PS1 ranges from 5 to 15 micrometers.

Like all modern mobile profilometers, the device works not only from the electrical network, but also from the built-in batteries. There are also models with removable batteries.

How to choose?

The selection of the meter will be directly dependent on the type of surface and destination, the complexity of the product being checked. Stationary contact and contactless profilometrs allow you to obtain a more accurate and detailed assessment of the roughness of the material. Roughness of solid surfaces, such as high-carbon steel parts, it is better to measure with diamond dipstick devices. Make an operational or partial assessment of material processing is more convenient to portable Portable instrument.

Optical contactless meters are designed only to scan purified materials – dust and contamination can significantly distort the result.

In specific production conditions for checking such surfaces, it is recommended to use contact profilometers with solid diamond tips, otherwise the roughness indicator will be incorrect.

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