How to select the type of metallographic sample cutting machine? Key points of selection and analysis of LQG‑350DT model

metallographic cutting is the first process of metallographic sample preparation, and the cutting quality directly determines the test results of subsequent inlaying, grinding and polishing, and microscopic observation. The samples will be directly scrapped due to overheating burn, chipping of the cut surface and substandard size, so it is very important to select the cutting machine. In this paper, the core selection dimensions of metallographic cutting machine are sorted out, and the equipment functions, hardware details and applicable scenarios are explained in combination with the LQG‑350DT manual-automatic metallographic sample cutting machine.

 1. Five Key Points of Metallographic Cutting Machine Selection

1. Define the sample size and match the cutting capacity of the equipment.

The first step of model selection is to confirm the daily sample specifications: the maximum diameter of circular workpiece, the length, width and height of square sample, and check the maximum cutting diameter of equipment, Y-axis feed stroke and the size of workbench. If the selection is too small, large samples cannot be clamped; Blind selection of large models will cause budget waste.

 Focus on: outside diameter specification of grinding wheel, which directly limits the maximum cutting capacity of the equipment and needs to match the maximum cross section of the sample.

 2. Determine the use mode: manual, automatic or automatic.

- Pure manual type: Suitable for small batch, sampling inspection, scientific research and teaching, with low cost, relying entirely on manual control of feeding force, requiring high experience of operators and poor consistency of cutting surfaces.
-Full-automatic model : It is suitable for mass quality inspection in factories, with programmed parameters, unattended cutting and good section consistency, but the price is high, and some simple sampling scenes are cumbersome to operate.
- Manual-automatic integrated model : It is a cost-effective choice for laboratories at present, considering both flexible sampling and batch automatic sample preparation, fast sampling and manual mode, and batch standardized cutting and automatic mode switching.

3, cooling system, to prevent sample tissue burns.

High-speed friction of cutting grinding wheel will produce a lot of high-temperature heat, and high temperature will change the metallographic structure of metal, which will directly lead to the distortion of testing data.
The selection must confirm whether the equipment has a circulating cooling spray system, whether the cooling liquid can be fully sprayed into the cutting area to take away the cutting heat, and avoid overheating and burning of the sample. Heat-sensitive metal materials require higher cooling performance.

 4, control system and cutting process capability

-Basic model: ordinary key control, only fixed rotation speed and feed speed, and the parameters are not adjustable.
-Numerical control touch screen model: The touch screen has man-machine interaction, and the feed speed, feed distance, pulse cutting mode and spindle speed can be set freely, and the cutting stroke data can be displayed in real time. The cutting process can be flexibly adjusted according to mild steel, hardened steel, non-ferrous metals and nonmetals, resulting in higher surface finish.

 5, safety protection and equipment hardware reliability

The safety of laboratory equipment can not be ignored, and priority should be given to the following functions: safety door lock interlocking, grinding wheel clamping protection, emergency stop button, automatic reset after cutting, overload shutdown and so on. At the same time, verify the motor power, fixture clamping capacity and fuselage rigidity; The rigidity of the fuselage is poor, and the cutting jitter is great, which will cause problems such as sample edge collapse and notch inclination.

 II. Product Features and Hardware Details of LQG‑350DT Metallographic Sample Cutting Machine

(Actual shooting of equipment: totally enclosed cutting protective cabin, with touch-sensitive touch-screen operation panel integrated on the right side, and cooling pipeline, threaded strong clamp assembly and manual feed handwheel visible in the cabin)

LQG‑350DT belongs to * * CNC metallographic sample cutting machine with hand-to-hand integration, which takes into account the research and development of small samples in scientific research institutions and batch testing in factories, and adapts to the preparation of various kinds of metal and nonmetal samples.

 Highlights of core functions

1. Manual/automatic free switching, three cutting modes * *
Support manual continuous cutting, manual pulse cutting and automatic pulse cutting. Temporary sampling is quickly cut by manual mode; Automatic pulse cutting is started in batch sample preparation to realize unattended operation, and the ratio of advancing and retreating knives can be adjusted by user. Pulse cutting effectively reduces the thermal influence of cutting, and the cutting section is smooth and smooth.
2. Touch screen numerical control system, with visible and controllable parameters * *
The whole machine is controlled by touch screen integrated machine, and all cutting data are displayed intuitively on the screen; * * The feed distance can be set at will, the Y-axis feed stroke can be tracked and displayed in real time, and the positioning is accurate * *. Operators can intuitively grasp the cutting process and bid farewell to blind cutting.

details: the operation panel is equipped with an independent red mushroom head emergency stop button, which can be stopped by one button in case of emergency.

3.  Variable frequency spindle speed regulation, suitable for samples of various materials * *
The cutting motor is equipped with frequency converter, and the spindle speed * * 10003000 r/min is infinitely adjustable * *. The rotation speed of soft aluminum and copper materials is lowered, and the rotation speed of high-hardness quenched steel materials is raised. The cutting process of different materials is matched to reduce the loss of grinding wheels and the edge collapse of samples.
4.  Multiple safety protection design * *

-Automatic detection and shutdown of grinding wheel clamping: the cutting blade is jammed and overloaded, and the equipment automatically stops to protect the grinding wheel, motor and sample;
-Door safety lock: the protective cover of the cutting room is safely interlocked, and the door opening equipment cannot be started to prevent debris from splashing and injuring people;
-Automatic reset after cutting: after cutting in automatic mode, Y-axis feed automatically returns to the starting position, which is convenient for taking and placing samples and improving the convenience of operation.

5.  Built-in circulating cooling system to protect metallographic structure * *
The blue cooling spray pipeline is arranged inside the cutting chamber, and the cooling liquid continuously sprays the cutting area during the cutting process, taking away the friction heat in time, * * effectively avoiding overheating and burning of the sample, ensuring the integrity of the original metallographic structure and ensuring the authenticity and validity of the subsequent metallographic analysis results * *.
6. Strong thread and strong fixture, stable clamping * *
The cabin is equipped with a threaded strong clamp, the workbench is provided with a T-shaped groove, and the platform size is 326 × 280 mm; The maximum cutting diameter of a circular sample can reach φ 100mm, and a rectangular sample can cut workpieces with a height of 70mm and a depth of 100mm, and round bars, squares and special-shaped parts can be stably clamped.

 Key technical parameters of LQG350dt


| Project | Parameters |
| --- | --- |
| Model | LQG‑350DT |
| Cutting mode | Manual continuous cutting, manual pulse cutting, automatic pulse cutting, Y-feed |
| Automatic feed speed | 0‑200mm/min adjustable |
| Specification of grinding wheel | φ 350× 2.5× φ 32mm |
| Maximum cutting diameter | φ 100mm |
| Y-axis travel | 270mm |
| Spindle speed | 1000‑3000r/min stepless speed regulation |
| Motor power | 3KW |
| Cutting platform | 326×280mm with 12mmT groove |
| Control mode | Touch screen integrated machine, external emergency stop button |
| Power supply | 380V 50Hz tn-s |
| Overall dimension | 900×840×720mm |
| Weight of the whole machine | 190Kg |

 III. LQG‑350DT Applicable Scenes

1.  Quality inspection laboratory of industrial and mining enterprises * *: incoming inspection of parts, metallographic examination of heat treatment, automatic cutting of batch samples;
2. Laboratories of universities and scientific research institutes * *: research and development of new materials, manual and automatic switching, taking into account small batch tests and routine sampling;
3.  Applicable samples * *: carbon steel, alloy steel, copper-aluminum nonferrous metals, ceramics and other non-metallic materials.

IV. Supplementary Suggestions for Selection

1. If the sample is generally larger than φ Φ100mm round bar, it is necessary to choose a model with larger grinding wheel specifications;
2. In cutting high hardness materials such as cemented carbide and ceramics, in addition to equipment, diamond cutting pieces need to be selected to further ensure the quality of the cut surface;
3. Give priority to the source manufacturers with complete qualifications, confirm the equipment quality assurance, operation training and spare parts supply service, and reduce the later maintenance cost.

This equipment is produced by Jinan Liling Testing Machine Co., Ltd., the enterprise has ISO9001, CE and other system certifications, and provides equipment delivery, debugging and operation training services.