Comparison of advantages and disadvantages of grating ruler, ball grating ruler, and magnetic grating ruler

Machine tool linear encoders (machine tool digital encoders) are used for measuring machine tool displacement, which can be roughly divided into three types: grating ruler, ball grating ruler, and magnetic grating ruler. Below, we will provide a detailed understanding of these three digital encoders * structure * accuracy comparison * product advantages * disadvantages. Comparison and comparison are convenient for everyone to understand the three types of digital encoders.

1¡¢ From the appearance structure of each product:

1. Grating ruler: Based on the optical glass engraving line as the measurement reference, the optical glass is installed inside the aluminum alloy ruler body and the reading head and other accessories to form a grating ruler. The aluminum alloy is semi sealed in design, as shown in the following figure:

2. Ball grid ruler: Based on the subdivision of the ball into measurement benchmarks, the ball grid ruler is composed of an alloy ruler body and reading head accessories, with a fully sealed design, as shown in the following figure:

3. Magnetic grating ruler: Based on the principle of magnetic tape engraving (burning position), magnetic materials are used to form the ruler body and reading head accessories to form the magnetic grating ruler. It has an open or semi sealed design, as shown in the figure below:

From the perspective of appearance and structure, it is preferable for the ball grid ruler to be fully enclosed, with a high hardness alloy ruler body that is sturdy and durable. The second is the grating ruler semi enclosed, optical glass measurement benchmark, aluminum alloy ruler body, with average durability. The third is the magnetic grating ruler semi enclosed and open, using 3m adhesive for bonding, and optional aluminum alloy base, with poor durability.

2¡¢ Accuracy comparison:

Below, we will use Hangzhou Depu grating ruler, ball grating ruler, and magnetic grating ruler, all with a resolution of 0.005mm, as the test object to test the positioning accuracy and absolute accuracy of the product. The testing equipment is the Hangzhou Depu laser length measurement platform:

1. Positioning accuracy: The error of repeating a position and reaching this position each time is called positioning error:

   
   

2. Absolute accuracy: The error from zero point to the standard length, called absolute accuracy. The accuracy comparison between a 3-meter grating ruler, ball grating ruler, magnetic grating ruler, and a laser interferometer is as follows (using a 0.005mm resolution ruler):

From the perspective of positioning accuracy and absolute precision, you can choose the digital display product you need based on the accuracy that the processed product can achieve.

3¡¢ Advantages and disadvantages of three types of digital displays:

Grating ruler:

1. Grating ruler: The grating uses optical glass as the measurement reference, so its accuracy is high. The above experiments also verify its good accuracy. 2. The grating ruler adopts a semi sealed design, which has certain waterproof, dust, and iron chip capabilities. During use, water, oil, iron chips, etc. entering will accelerate the damage of the grating ruler (you can see the video of Depp's experiment in this regard).

3. The sales price of grating ruler is low, and there are many optional devices for installation, making it widely used.

4. Service life: Depending on the type of machine tool installed and the usage environment, the overall service life is about 1-5 years. If the usage environment is good and there is no water, oil, iron filings, or low vibration, the service life will be long. If the machine tool has oil, water, iron filings, dust, and high vibration, the product life will be short.

5. Advantages of grating ruler: Short stroke ruler, grating ruler can make high-precision ruler, good temperature characteristics, and low price, with a relatively large usable space.

Ball grid ruler:

1. The ball grid ruler has good accuracy and is suitable for most machine tools. The above tests have also verified its good accuracy.

2. The ball grid ruler adopts a fully sealed design, with an alloy ruler body that is waterproof, dustproof, iron shavings resistant, and vibration resistant, and is not affected by the environment, so it has a long service life (you can watch Depp's test video in this regard).

3. The disadvantage of ball grid rulers used to be based on high import sales prices. Now, Hangzhou Depu's production of ball grid rulers can achieve a price that most customers can accept, with excellent quality and a wide range of optional installation equipment. They are widely used, such as milling, turning, boring, gantry and other machine tools. For more information, please consult Hangzhou Depu Measurement Equipment Co., Ltd.

4. The service life of the ball grid ruler is generally more than 10 years, and its ruler body can achieve the same service life as the machine tool. Due to its waterproof, oil resistant, iron chip resistant, vibration resistant, etc., it has few faults during the use of the machine tool, is stable and reliable, and basically has no faults. Therefore, it is commonly seen in important equipment such as boring machines, gantry machines, and vertical lathes. As the price of the ball grid ruler decreases, it is more commonly used in small equipment such as lathes and milling machines.

magnetic grating ruler

1. The magnetic grating ruler adopts the principle of magnetic tape, and the magnetic tape reference signal is relatively wide, the signal is not very accurate, and the accuracy is poor. The above laser experiments have also verified that it is more commonly used in situations where accuracy is not required or in rough machining equipment, with more automation equipment.

2. Magnetic grid rulers come in both open and semi closed types. The magnetic grid strip is glued onto aluminum alloy or machine tools using 3m adhesive. The magnetic grid ruler itself is made of magnetic material and is glued with 3m adhesive. It can withstand water or oil for a short period of time without any problems, but it will swell and fall off in the oil-water environment over a long period of time. If the outer shell protection is relatively better, the magnetic grid still has demagnetization problems, resulting in signal loss and processing errors. The magnetic grid ruler processing environment is prone to attracting iron filings and causing signal loss, leading to incorrect display instrument numbers. Therefore, it is necessary to clean the ruler body with a towel and protect it (you can watch the relevant test video of Depu).

3. Advantages of magnetic grid ruler: The price of magnetic grid ruler is extremely low, and there are many rough machining equipment. Due to its low price, simple installation, and easy use by pasting, it is widely used in automation equipment.

4. Service life of magnetic grating ruler: Depending on the type of machine tool installed and the usage environment, the overall service life is about 1-3 years. If the usage environment is good and there is no water, oil, iron filings, or low vibration, the service life will be long. If the machine tool has oil, water, iron filings, dust, and more iron filings, the product life will be short, and the reliability or accuracy requirements are not high.

5. After careful consideration, Depp decided not to use magnetic grids as machine tools because the machining process caused iron filings to be attracted to the magnetic grids, resulting in signal loss and damage to the workpieces. (Many people would say that wiping with a cloth is enough, but once the workpiece has been machined, it cannot be wiped. Time cannot be reversed, wasting machining time and workpieces. Overall, magnetic grids cannot save money, so it is not recommended to use them as machine tools. Additionally, it is said that magnetic grids have high precision. Depp only wants to say that they are available, often at a higher price than ball grid rulers, but there is still a possibility of signal loss. In terms of reliability and stability, it is not recommended to use them. Related videos are available.).

Depp recommends using a ball grid ruler because it is more cost-effective to use for a long time, with one investment, longer use, better stability (corresponding to fewer processing errors), fewer malfunctions (later cost less, more cost-effective), can adapt to various usage environments, and can be used for a longer time. In mechanical processing, we only recommend ball grid rulers.

Boring machine, gantry, vertical lathe, we recommend ball grid ruler. Although ball grid ruler may be slightly more expensive, it has high stability, fewer faults, fewer processing errors, longer product life, and brings more savings and peace of mind when choosing (often one workpiece is several times more expensive than the number), so it is necessary to have a more stable digital display. If oil, water, dust, and iron filings are used for equipment such as cars, milling machines, etc., and the vibration of car sales is high, a ball grid ruler is used. If a lathe is equipped with a grating, the lifespan is basically about one year, which makes the grating ruler more expensive than the ball grid for long-term use. However, now there is no need to spend this money, which also brings a lot of instability, high product scrap, high failure, and extra money. So we still recommend the ball grid ruler.