How a Forklift Oil Pump Works in the Hydraulic System?

  • Working principle of forklift hydraulic system

The basics of the hydraulic system go like this: Confined oil has pressure on it from one side. That pressure forces the oil against a piston on the other side of the container. That transfers energy into the piston, forcing it upward. The piston cannot move in the opposite direction unless the pressure is released. In terms of the forklift hydraulic system, the pistons raise the forks and keep them lifted until the hydraulic pressure is released by the operator.

  • Composition and function of forklift oil pump

Forklift piston oil pump is mainly composed of small forklift parts such as pump body, seal, oil outlet and inlet valve etc. Its function is to suck the oil used by the forklift from the oil tank to generate a certain pressure of the oil to overcome the resistance of the oil filter and pipeline, and to ensure continuous delivery of sufficient oil to the oil injection pump.

Working principle diagram of forklift oil pump

 

 

  • The forklift oil pump is installed in the forklift hydraulic system. Now, let me introduce the safety technical requirements of forklift hydraulic system accessories.

Forklift hydraulic system accessories occupies an important position in the use of forklifts. Forklift working device accessories mainly rely on hydraulic system for lifting, tilting and other actions. The working condition of the forklift hydraulic system will directly affect the working condition of the forklift. Once the hydraulic transmission system parts of the forklift have malfunctions, it will inevitably bring direct unsafe consequences. Therefore, it is important for the safe operation and driving of the forklift to maintain the hydraulic system in strict accordance with the safety technical requirements. The following are the safety technical requirements for forklift hydraulic system:

  1. The oil level of the oil tank shall not be lower than the oil mark line of the oil level indicator. And the application of hydraulic oil shall comply with the regulations. At the same time, the oil shall be clean, and the filters shall not be blocked.

  2. The overflow valve should be sensitive and reliable; The nuts of the adjusting bolts must be complete; And the pressure regulation should meet the equipment requirements.

  3. The components, pipelines and joints of the forklift hydraulic system should be unblocked. There is no leakage of the seal, no friction with other accessories, and no aging or deterioration of the rubber hose. The internal leakage should be within the allowable range.

  4. The compression spring of the forklift multi-way valve must be intact, and the valve stem can be quickly back to position when eliminating the external force. The joystick should have a certain strength and rigidity, the surface should be smooth, without deformation. And the joystick should be positioned reliably, and not displaced due to vibration. The overflow valve should be sensitive and fully open when overloaded by 25%. And the nuts of the adjusting bolts should be fully tightened.

  5. Crawling, stagnation and significant impact should not occur within the rated speed range of each hydraulic cylinder.

  6. Each high-pressure hose should undergo a pressure test and meet the specified requirements.

  7. Various control valves should be safe, reliable, and sensitive.

The Maintenance and Common Faults of Manual Hydraulic Pallet Jack

Today, we will introduce the maintenance and common faults of manual hydraulic pallet jack to you as follows.

Daily Maintenance:

1. Adding oil

Check the oil level once a month. We recommend you to use 32# hydraulic oil.

2. Exhaust

Due to transportation or the inversion of the pump body, air is likely to enter the hydraulic pump. This will cause the failure to lift cargo when the pressure is suppressed in the rising position. You can operate exhaust according to the following steps: pull the top of the handle to the down position, then lift up. Thus repeat for several times.

3. Daily inspection and maintenance

Routine maintenance is indispensable, and the focus should be on the maintenance of wheels, core axis and rags. When finish handling, we should remove the items on the fork and lower the fork frame to the lowest position.

4. Lubricant

We should add all bearings and shafts with lubricating oil. We only need to add lubricating oil to all moving parts at monthly intervals or during each thorough inspection.

iron casting oil pump

Common faults:

Fault 1: The fork cannot rise to the highest position

Cause analysis: insufficient hydraulic oil

Repair method: add hydraulic oil

 

Fault 2: The fork does not rise

Cause analysis: there are impurities in the hydraulic oil, the pressure relief valve is not adjusted properly, or there is air in the hydraulic oil.

Repair method: replace clean hydraulic oil, adjust set screw, remove air.

 

Fault 3: The fork does not drop

Cause analysis: the piston rod of the cylinder is deformed due to unbalanced load, parts are damaged or deformed due to unbalanced load, and the pressure relief valve is not adjusted properly

Maintenance method: replace the piston rod or cylinder, repair or replace related parts, adjust the set screw,

 

Fault 4: Leakage

Cause analysis: worn or damaged seals, cracked or worn parts

Repair method: replace new seals, check and replace new parts

 

Fault 5: The fork drops when the pressure is not released

Cause analysis: maybe there is impurities in the hydraulic oil, air in the hydraulic oil, the seal is worn or damaged, or the pressure relief valve is not adjusted properly.

Maintenance method: replace clean hydraulic oil, remove air, replace new seals, adjust set screws

How to Avoid Ductile Iron Casting Rust?

How to Avoid Ductile Iron Casting Rust?

Yide iron casting is a leading casting supplier and machining factory in China, provides ductile iron casting oil pump, cast iron pipe, cast iron valve and so on. But Will These Iron Casting Rust?

Will Ductile Iron Casting Rust ?

Rust is a chemical reaction, because the chemical properties of iron are vivid, and it will rust after a certain time. Moisture is one of the substances that make iron rust. However, water alone will not cause iron to rust. Only when the oxygen in the air dissolves in the water, the oxygen reacts with iron in a watery environment to produce something called iron oxide, which is rust.

 How to Avoid Rust for Iron Casting?

Then, will ductile iron casting rust?The key is whether the anti-corrosion process of the ductile iron castings is in place. Qualified ductile iron castings are required to be lined with standard thick road cement. At the same time, the outer wall of the casting is required to be sprayed with zinc and coated with asphalt, and other epoxy paints may be selected.

There are some specific methods to prevent ductile iron castings from rust:

 

  1. Asphalt paint coating

Asphalt paint coating is suitable for gas pipelines. Preheating the ductile iron pipe before painting can improve the adhesion of asphalt paint and accelerate drying.

  1. Cement mortar lining with special coating

This internal anti-corrosion measure is applicable to sewage pipelines, which can improve the corrosion resistance of the lining.

  1. Epoxy coal asphalt coating

Epoxy coal asphalt coating is suitable for both gas pipelines and sewage pipelines. It is a two-component coating, which has high adhesion and a very smooth surface.

  1. Epoxy ceramic lining

Epoxy ceramic lining is suitable for sewage pipes and gas pipelines. However, due to difficulties in manufacturing process and high cost, epoxy ceramic lining has certain limitations in use. The epoxy ceramic lining has high adhesion and smoothness, and is an excellent anti-corrosion coating.

  1. Aluminate cement coating or sulfate cement coating

These two special cement coatings are suitable for internal anti-corrosion of sewage pipes, which can improve the resistance to acid and alkali components in sewage.

Yide casting has 27 years’ casting & machining experience, known as an iron casting manufacturer in China, specialized in the grey iron cast, ductile iron cast, and brass iron casting, and also provides machining service for the rough iron casting pipe or iron casting pump products etc. So Yide casting is a one stop solution of casting, if you have demands of casting, please don’t hesitate o contact us for more details.

The Difference Between High Manganese Steel and Stainless Steel

The difference between high manganese steel and stainless steel

 

Compared with 304 stainless steel, high manganese steel increases the manganese content and reduces nickel, and with weaker corrosion resistance. Meanwhile, the appearance glossiness of high manganese steel is not as bright as 304 stainless steel. However, high manganese steel is still widely used in many fields because of its advantages of low cost.

 

High manganese steel is not suitable for use in chemical environments such as acids and alkalis. Nevertheless, It is ideal for the manufacture of tableware, indoor water storage equipment, and engineering non-critical structural parts. 304 stainless steel is of course better in many aspects. But high manganese steel still has  advantages, as long as it is produced by a regular manufacturer.

At present, the national standards do not clearly define the grade of stainless steel materials for containers or tools for food. This means that electric kettles made of non-304 stainless steel are not substandard products.

 

Food-grade stainless steel refers to the stainless steel material that complies with the “National Standard of the People’s Republic of China/Sanitary Standard for Stainless Steel Tableware Containers” GB 9684-88, and its lead and chromium content is much lower than that of ordinary stainless steel.

All kinds of food storage containers and food processing machinery should use austenitic stainless steel (1Cr18Ni9Ti, 0Cr19Ni9, 1Cr18Ni9). And all kinds of tableware should use martensitic stainless steel (0Cr13, 1Cr13, 2Cr13, 3Cr13) should be selected.

How to improve the quality of large steel castings

The use of large steel castings is relatively common, such as mechanical equipment parts and precision steel castings on automobiles, which have relatively high quality requirements for products. In order to ensure the quality of these products, large steel castings manufacturers should control from a relatively basic process:

  1. According to the drawings provided, we should select the appropriate casting equipment. This basically guarantees the product quality of the steel castings. In the process of producing, solve the problems effectively, so as not to cause bigger losses.

 

  1. We should repair the surface in the first place if the product is defective in the process.

 

 

And then, what are the precautions in the process of producing large steel castings?

  1. Precautions for heat treatment of large steel castings

The strength level of large steel castings is close to the forged steel, with poor plasticity and resistance, uneven and not dense inside, large internal chemical composition error, poor thermal conductivity and messy structure. Therefore, it is necessary to pay special attention to eliminate internal stress and prevent cracking during heat treatment, but not necessary to take the harm of hydrogen into account. When formulating the heat treatment process, you can refer to the TTT curve, CCT curve and hardenability curve of the same steel grade. Meanwhile it is necessary to pay attention to the influence of uneven chemical composition, coarse grains and other casting defects.

 

  1. Partial heating phenomenon of large steel castings

There are many factors for partial heating phenomenon of large steel castings, mainly the following three types: 1) System overload, which is mainly manifested in excessive pressure or speed. 2) Oil outlet pipe is too thin, which leads to high oil flow rate and generates a lot of heat. 3) Poor cleanliness of the oil, which leads to increased internal wear, reduced volumetric efficiency, and oil leakage and throttling from the internal gap to generate heat.

 

  1. The reason of infiltration during the processing of large steel castings

Infiltration is actually a method of porosity treatment, especially micropores which can not be seen with naked eye. The appearance of micropores will cause leakage of the sealing medium, and increase the wear of the machining tool. Besides, micropores will also increase the cost, so that the quality of the product cannot be guaranteed. In the application process of the product, it will lose its function.

  1. Causes of subcutaneous pores in large steel castings

The generation of subcutaneous pores is a comprehensive reaction of improper operation of various links and procedures in the casting process. The reasons for the formation are complex and there are many influencing factors. We should pay attention to every operator and process involved.

 

In the casting process, the structure of large steel castings needs to be repaired for the parts after molding. There are many ways to repair the mold. 

 

  1. After the parts are moulded, there will be some places that are soft and not tight. Use a knife to loosen and use a tool to cram.
  2. The damaged part of the intersection of the two walls can be glued with sand with a knife, wiped to the gap and then smoothed.
  3. Large pieces of sand can be repainted with muddy water to re-patch.
  4. If there is a groove in large area, you can dig out the part first, and then repair it.

How To Avoid Poor Quality Steel Casting During Heat Treatment?

The strength level of large steel castings is close to forged steel, but with poor plasticity and resistance. At the same time, large steel castings also have problems such as uneven and not dense inside, large internal chemical composition error, poor thermal conductivity and messy structure.

Therefore, it is necessary to pay special attention to eliminate internal stress and prevent cracking during heat treatment. However, there is no need to take the harm of hydrogen into account. When formulating the heat treatment process, you can refer to the TTT, CCT and hardenability curve of same steel grade. Meanwhile, we should also take the influence of uneven chemical composition, coarse grains and other casting defects into account.

Precautions for the heat treatment of large steel castings

 

  1. Suitable temperature adjustment.

Due to large volume and tonnage, large steel castings simply form large internal and external temperature differences and stress during heat treatment. Therefore, we should pay attention to its heating and cooling rate. This can largely reduce the temperature difference and stress of steel castings.

  1. To ensure excellent circulation of the furnace gas.

When installing the furnace, the casting should be placed on the horn of appropriate height. The placement of the horn should ensure excellent circulation of the furnace gas and prevent the deformation of the casting. For important large castings, a sketch of the furnace installation should be made to specify the technical requirements, and indicate the orientation of the thermocouple when drawing an external thermocouple.

  1.  It is necessary to stress relief after heat treatment.

Large-scale castings (except high-manganese steel) should relief stress after heat treatment, welding repair, correction, machining, and cutting riser waiting.

  1. After heat treatment, too many cuts are not allowed.

Yide casting has rich experience in heat treatment of casting, with 27 years’ experience. If you have any problem with iron casting, brass casting, or steel casting, or you are looking for an experienced casting manufacturer in China, please don’t hesitate to contact us for more details.

How To Detect The Large Gray Iron Castings?

The detection method of large gray iron castings

Quenching, the detection method of large gray iron castings, is generally divided into three stages: vapor, boiling and convective heat transfer.

When the hot gray iron casting is put into the quenching medium, the medium around the casting is immediately heated to the boiling point and vaporized. Thus forms a superheated steam film on the surface of the castings to separate the casting from the quenching medium.

Due to the poor thermal conductivity of the steam film, the casting surrounded mainly depends on radiation and steam conduction. At this point, the casting cools slowly until the steam film ruptures and disappears, entering into the boiling stage.

Due to the presence of carbon nanotube particles, the oil-based carbon nanotube fluid breaks the formed bubbles, reduces the time of vapor stage, and enables different parts of the grey iron cast to enter into the boiling stage almost simultaneously with a high cooling rate. In the low-temperature stage of the cooling process, the cooling rate is relatively low. This greatly reduces the transformation stress of the martensite structure and the quenching cracking and distortion rate of the workpiece.

 

 

For the reasons mentioned above, the hardness of the sample in the oil-carbon nanofluid is significantly greater than that in 30# engine oil.

The failure modes of the cavity surface layer are mainly thermal fatigue cracks. The working characteristics of the low-pressure casting mold are affected by thermocycling. After each liquid metal is formed, the mold cavity is cooled by water, steam, air and other media. The working state of the mold cavity is repeated heating and cooling. As a result, the surface metal of the mold cavity undergoes repeated thermal expansion and contraction. That is, repeating tensile and compressive stress, resulting in cracks on the surface of the mold cavity.

Therefore, hot die steel needs high thermal fatigue resistance. The main factors affecting the thermal fatigue resistance of steel are as below:

1. Thermal conductivity of steel

The high thermal conductivity of steel can reduce the heating of the metal on the surface of the mold. Thereby it can reduce the tendency of steel to thermal fatigue. It is generally believed that the thermal conductivity of steel is related to the carbon content. The higher the carbon content, the lower the thermal conductivity. Therefore, it is not appropriate to use high carbon steel for hot die steel. Generally, we chose medium carbon steel (Wc=0.3%~0.6%) in production. If the carbon content is too low, the hardness and strength of the steel will decrease.

 

2. The critical point of steel

The higher the critical point (Ac1) of steel, the lower the tendency of steel to thermal fatigue. Generally by adding alloying elements such as Cr, W, Si, etc. to increase the critical point of steel.

 

The test result is invalid for the following causes:

1. Improper installing of the sample on the test machine, or improper operation of the test machine.

2. The surface of the sample has casting defects or improper processing of the sample (such as transition fillet, surface roughness and unsatisfactory size, etc.).

3. the tensile sample breaks outside the gauge distance.

4. obvious casting defects on the tensile sample port.

In the above cases, we should re-sample on the same test block or from the same batch of poured test blocks and test again.

 

If you want to know more about grey iron casting, you are welcome to visit our Yide Casting factory – JM casting.

If you are looking for an excellent grey iron casting for automobile engine cylinders iron cast, gears gray iron cast, speed grey iron cast wheels, casting gray iron brake discs and iron cast grey casting drums, and grey cast iron large machine tool bases, forklift casting, pipe grey iron parts, manhole over grey cast iron, Yide casting is a good choice for your casting parts manufacturing, please feel free to contact us for more details.

What Is The Cooling Process of Stainless Steel Castings ?

Stainless steel castings are one of the products produced by Yide Casting all year-round. Yide Casting have been manufacturing all type of steel casting items in 27 years. For example, double burner stainless steel, cast steel river, cast steel swivel, stainless steel grill grates, cast steel plate, etc.

The knowledge about stainless steel castings is also our concern. We all know that in the completion of the casting, cooling is also a step that cannot be underestimated.

Here’s a brief introduction of the cooling process of stainless steel castings:

The temperature will change after pouring the liquid metal into the casting mold.

After the liquid metal is injected into the mold, the heat exchange follows. The continuous decreasing temperature of the liquid metal and the increasing temperature of the mold indicate it.

There is an intermediate layer between the mold and casting.

The heat transfer system during the cooling and solidification process contains the casting mold and the forming metal. However, practice has proved that the inner surface temperature of the  mold is different from the surface of the casting. That means there is an intermediate layer between the mold and casting.

The heat transfer system of the casting during the cooling and solidification process is unstable .

The formation of the intermediate layer owing to the shrinkage of the metal in all directions and the expansion of the mold after heating. May it’s because of the paint layer on the surface of the mold, or an intermediate layer that has both gaps and paint.

Therefore, the heat transfer system of the casting during the cooling and solidification process is unstable. And the system is composed of casting, intermediate layer and mold.

 

 

The intermediate layer is the key to control the heat exchange.

Both the cross-section of casting and mold are metal. So when the cooling of the casting and the heating of the mold is not very intense, the cross-section has similar temperature distribution rules or thermal resistance. Thus the intermediate layer between the casting and the mold has an important effect on the entire heat transfer system.

In the casting-intermediate-mold system, most of the temperature drops on the intermediate layer. This is the case when the surface of the metal coats with thick paint.

The characteristic of this type of heat transfer is that the temperature difference between the cross-section of casting and mold is smaller than that of the intermediate layer.

Therefore, it can be assumed that the temperature on the cross-section of casting and mold is actually evenly distributed. And the heat transfer process mainly depends on the thermophysical properties of the coating layer. This means the thermal resistance of the intermediate layer is the key to control the heat exchange.

Leading Steel Casting Supplier In China

At the end of the article,  I want to recommend Yide Casting manufacturer – with JM casting factory, covering an area of 20000 sqm, over 200 employees. JM casting is famous of quality and word of mouth, without promotions and marketing ways. Thus if you are looking for a casting factory, please don’t hesitate to contact us for more details.

 

How to Manufacture Quality Cast Steel

How to Manufacture Quality Cast Steel

As we all know, the price of the steel cast is higher than the iron casting. But why?

If cast iron vs stainless steel, the mechanical properties of stainless steel casting are higher than that of cast iron, but its casting performance is worse than that of cast iron. However, the manufacturing of cast steel is more difficult than cast iron, thus its cost is higher.

Stainless steel casting belongs to investment casting or precision casting, with a relatively high melting point, and the molten steel is easily oxidized, due to poor fluidity of molten steel and large shrinkage rate. From a practical perspective, stainless steel casting is suitable for casting of various types and alloys.

I will show you how to produce quality cast steel as follows.

1. Poor liquidity of the molten steel.

Firstly, due to the poor liquidity of the molten steel, the wall thickness of the steel castings should not be less than 8 mm, in order to prevent the cold shut and misrun.

2. Simple structure requirement.

The structure of pouring system strives to be simple, and the sectional dimension is larger than that of cast iron.

3. The requirement of Suitable Casting Temperature.

We should adopt dry casting or hot casting, and the casting temperature should be at 1520-1600 ℃.

The fluidity can be improved since the casting temperature is high with a large superheat, thus the liquid stays for a long time.

However, if the pouring temperature is too high, it will cause defects such as coarse grains, hot cracks, pores and sand burning. Therefore, the casting temperature of small, thin-walled and complex casting should be at the melting point +150 ℃; and of large, thick-walled casting +100 ℃.

 

 

We must take these measures to prevent the occurrence of shrinkage holes and cracks in stainless steel castings.

1. Making the wall thickness uniform, and avoid sharp and right-angle structures.

2. Adding sawdust to sand mold, and coke to the sand core.

3. Adopting hollow sand core and oil sand core to change the deformability and permeability of the sand mold and core.

 

Yide Casting is a leading casting foundry in China, with 27 years’ casting experience, provides casting & machining service for our casting customer. Here, we have a steel casting foundry partner, which we have cooperated for many years. Yide casting machines casting products, such as reel steel cast, cast steel plate, 6 inch steel caster wheels, burner stainless steel etc. If you are looking forward to a professional casting manufacturer, please don’t hesitate to contact us, and welcome to visit our JM casting factory in China.

The Distinction between Sand and Metal Casting  

Sand casting literally is a casting method with sand as a moulding material, and is a traditional casting process, which generally uses gravity casting, and low-pressure or centrifugal casting for special requirements.

Sand casting’s application is very broad. The mold used, initially wood, but now changed to aluminum alloy mold or resin mold due to some drawbacks. Compared with metal casting, sand casting has advantages, such as low price, high fire resistance, but still shortcomings.

The main raw material of metal casting is heat-resistant alloy steel. Metal casting is a modern casting process, and generally uses gravity casting and pressure casting. However, metal casting is not suitable for small-lot and large production, and not for copper alloys, but applied to castings of aluminum, zinc and magnesium.

Now let me introduce the advantages and disadvantages of metal casting and sand casting in details:

Advantages of metal casting

1. The metal mold has a faster cooling rate and a denser structure of the casting, which can be strengthened by heat treatment, and its mechanical performance is about 15% higher than that of sand casting.

2. The casting quality of metal casting is stable, the surface roughness is better than sand casting, and the scrap rate is low.

3. Good working conditions, high productivity, easy for workers to master.

Disadvantages of metal casting

1. The metal type has large thermal conductivity and poor filling ability.

2. The metal type itself has no air permeability. Corresponding measures must be taken to effectively exhaust.

3. The metal type has no retreat and is easy to crack and deform during solidification.

 

Advantages of sand casting

1. Compared with other casting methods, sand casting has lower cost, simple production process and short production cycle.

2. Because the molding materials used in sand casting are cheap and easy to obtain, the mold is easy to manufacture, and it can be adapted to single-piece production, batch production and mass production of castings.

Disadvantages of sand casting

The quality of molding sand and core sand directly affects the quality of castings. Poor quality of molding sand will cause defects such as pores, sand holes, sand sticking, and sand inclusion in the casting.