Why Is The New Covenant Better

Our text for this post is taken out of Hebrews 8 where the writer quoted the prophet, Jeremiah. We will see how the New Covenant is different from the old one. And why it is better. Click on the link below to read today's post. #BibleStudy #Devotions #Hebrews

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God's Judgment And Its Consequences

Today's chapter in Ezekiel is not an enjoyable one to read. If it were a movie, it would not be appropriate for Christians to view. But it is part of the Bible and if you read today's post you will see that it's a good teaching tool. Click on the link below to read it. #BibleStudy #Devotions #Evangelism #Ezekiel

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UHMWPE sheet is widely used in various fields such as fenders, carriage slides, coal bunker linings, roller skates, railway, highway and bridge bearing gaskets; Cnc Machining UHMWPE profiles can be prepared by machining the sheet, or obtained by injection molding

5.1 Compression molding

(1) Compression molding process

Compression molding is the earliest processing method for UHMWPE machining, and the process flow is shown in Figure 12. The method is not affected by the molecular weight and fluidity of the resin raw materials, and produces products with small internal stress and warpage deformation, simple equipment, low production cost, and low production efficiency.

In addition to the traditional compression molding process, the preparation methods of the sheet include:

• Extrusion molding. Use a plunger extruder for reciprocating batch extrusion or a screw extruder for continuous extrusion;
• Gas-assisted extrusion molding. During the screw extrusion process, a stable gas is injected between the die and the melt material to provide full-slip boundary conditions on the wall surface and reduce the frictional resistance between the melt and the flow channel;
• Ultrasonic powder molding method. Use ultrasonic vibration to quickly heat and plasticize the powder itself and then mold it;
• High-speed impact molding. At the temperature near the melting point, the mold filled with powder is subjected to high-speed impact and then sintered.

All of the above methods can improve the production efficiency of plates, but they are not easy to form larger products, and are limited in actual production.

(2) Plate modification technology

UHMWPE sheet has low surface hardness, easy fatigue wear, poor heat resistance and creep resistance, which restrict its application in some specific environments. In order to improve these deficiencies, domestic and foreign scholars have done a lot of research on molding resin or product modification, the main methods are polymerization modification, filling modification, cross-linking modification and so on.

Using new catalysts or in-situ polymerization to modify UHMWPE resin from the catalytic polymerization stage can prepare resins with specific molecular chain structures or compound modified resins that are uniformly mixed at the molecular scale, but the technical barriers are high; filling modification is simple and easy to implement However, there are problems of filler agglomeration or poor compatibility; cross-linking modification can better improve wear resistance and heat resistance. Among them, chemical cross-linking is more sensitive to the amount of cross-linking agent, and the residual instability after radiation cross-linking The degradation of free radicals and oxidative components has an effect on the properties of composite materials.

The author’s research group in this paper prepared UHMWPE composites with good self-lubrication, thermal conductivity, wear resistance, creep resistance and load-bearing capacity through solid-phase grafting, organic-inorganic hybridization and other methods. The large amount of frictional heat accumulated in the friction process cannot be conducted and plastic deformation occurs, which brings about potential safety hazards. Successfully prepared high wear resistance, high load bearing, and long cumulative displacement that can meet the needs of highway and railway bridge bearings. UHMWPE profiles.

5.2 Injection molding

(1) Injection molding process

Injection molding is the most efficient production method for large-scale preparation of various UHMWPE wear-resistant profiles. Compared with ordinary plastics, UHMWPE injection molding has the following difficulties: resin is difficult to feed, difficult to plasticize; melt viscosity is large, easy to block; injection molding is difficult to compact; product cooling is easy to deform.

Japan’s Mitsui Petrochemical Company realized the injection molding and commercialization of UHMWPE in the 1970s. Its injection molding technology is actually a combination of plunger injection and compression molding, which has the defects of poor plasticization, slow heat transfer and long molding cycle. ; Later, the reciprocating screw injection molding technology was developed, and the melt was sheared and stretched by the reciprocating screw, which solved the problems of poor plasticization.
In the 1980s, Beijing Plastics Research Institute improved the reciprocating screw to complete UHMWPE injection molding using high pressure and high speed injection technology. However, due to the low clamping force of domestic injection molding machines and the backward operating system, the stability of injection molding products was poor. In addition, UHMWPE injection molding is carried out by plunger push injection machine, multi-plunger injection machine, and plunger stamping injection machine, but there are disadvantages such as poor plasticizing effect, long molding cycle, and small melt amount.

In recent years, some companies have used reciprocating screw injection molding machines to inject flow-modified UHMWPE, but so far, injection molding technology has not been applied on a large scale in the field of UHMWPE.

The research shows that the screw groove of the feeding section is of equal depth, the screw groove of the compression section is gradually shallower, the homogenization section is divided into two sections, the deep screw groove and the shallow screw groove, and the nozzle is divided into a cylindrical cavity, a conical cavity, a nozzle hole and an inverted conical cavity. The design of the machine can promote the material to be gradually plasticized in the barrel and achieve smooth injection. The movable cavity technology is adopted, the cavity is expanded when filling the mold, and the cavity is compressed when the mold is clamped, so that the melt compaction can effectively improve the shrinkage problem of the product. . The order of the influence of various process parameters of the screw injection molding machine on the tensile properties of the product is injection pressure > injection speed > temperature in the metering section > screw speed.

The author of this paper believes that UHMWPE is easy to slip and can be fed with a deep screw groove design; a reasonable distance between the screw and the barrel can achieve full shear melting of high-viscosity melt and avoid screw locking; appropriate nozzle diameter can provide sufficient shear And avoid poor discharge; appropriate injection pressure and clamping force can ensure that the mold cavity is filled without overflowing; the variable mold temperature technology of high mold temperature filling and gradually decreasing mold temperature and pressure can also effectively solve the problem of product shrinkage.

(2) Modification technology of injection molding raw materials

Much of the focus on modification of injection-molding grade resins is to improve fluidity, including polymerization modification and blending modification. For example, bimodal polyethylene, solvent oil-containing resin, lubricating modifier-containing resin, etc. are prepared by new catalysis and polymerization processes; in addition, the processing performance of 3d printing and UHMWPE materials is improved by blending with components that improve the fluidity of the matrix.

HDPE and UHMWPE have good compatibility, UHMWPE/HDPE blending is a more convenient and effective method for UHMWPE flow modification; nanoparticles make composite materials have the characteristics of organic, inorganic and nanomaterials, and nanoparticles are introduced by in-situ polymerization , which can prepare injection-molding grade composite materials with uniform dispersion; use new catalytic polymerization technology such as single active center to develop new resins with both narrow molecular weight distribution and long-chain branched structure and low entanglement degree, which can solve the problem of processing performance and mechanical properties. The contradiction between them is also a research direction worth looking forward to.

Improving the fluidity of the resin can avoid problems such as melting glue and injection difficulties. The filling method also needs to solve the problems of loose product structure and serious shrinkage. Only when the fluidity modification is matched with the injection molding process and equipment can the final injection molding products with stable comprehensive performance and excellent quality be formed.

5.3 Artificial joints

At present, more than 90% of the artificial joint materials on the market are made of UHMWPE material. There are about three million joint replacement surgeries in the world every year. The wear and damage of UHMWPE components are the main factors affecting the life of artificial joints.

(1) Preparation process

UHMWPE artificial joints can be prepared by two methods of plunger extrusion and molding, and then modified and processed to obtain artificial knee joints, hip joints and other products. Compression-molded UHMWPE has an isotropic crystal orientation, while plunger extruded material has a slightly different crystal morphology with distance from the centerline. These crystal morphology differences can lead to subtle differences in fatigue crack growth behavior, Thereby affecting the phenomenon of osteolysis. Therefore, the use of molded UHMWPE molding or pom cnc machining is currently the mainstream of artificial joints.

(2) Research progress

UHMWPE was first used to make artificial joint liners and pads in 1960. At present, the wear resistance of UHMWPE base resin cannot fully meet the long-term use of joints. Research institutions and enterprises such as Massachusetts General Hospital have developed cross-linked UHMWPE, which greatly reduces joint wear and tear. FDA (FDA) approved for clinical use.

Subsequently, European and American countries invented vitamin E polyethylene, which has both anti-oxidation and wear resistance properties, and was approved by the FDA for clinical use in 2009. my country has gradually used UHMWPE to make joint liners since 1990, but the molecular weight, molding process and joint manufacturing process of domestic UHMWPE are relatively backward, the clinical life of artificial joints is short (about five years on average), and complications caused by wear and tear serious.

Increasing the entanglement density of UHMWPE by melt annealing can improve its amorphous region microstructure, thereby reducing the osteolysis of UHMWPE (i.e., grinding slag due to wear); however, the effect of melt annealing is limited and cannot effectively maintain high entanglement. state, the use of radiation crosslinking to reduce the chain mobility required for large-scale plastic deformation can slow down the formation of surface debris; however, secondary thermal processing after or during radiation melting can lead to oxidative degradation of the material , causing a decrease in crystallinity and strength, and using vitamin E as an antioxidant for medical-grade UHMWPE can eliminate residual free radicals in highly cross-linked UHMWPE artificial joints.

Recently, researchers found that the flavonoid natural antioxidants rutin, quercetin and tea polyphenols are more antioxidant than vitamin E. The author’s research group cooperated with key domestic artificial joint research units and enterprises to first obtain UHMWPE resin with reasonable molecular weight, distribution, particle size and distribution, and metal residue and comprehensive properties that meet the requirements of implant-grade standards; Research on modification of cross-linking, antibacterial and anti-oxidation.

The Message Of God Must Be Proclaimed

Many of the prophets in the Old Testament had a tough time proclaiming the message of God. Ezekiel was one of those prophets. His messages were often rejected. What about God's Message today? Click on the link below to read more about it. #BibleStudy #Devotions #Evangelism #Ezekiel

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Plastic processing, also known as plastic molding, is the process of processing plastics or synthetic resins into plastic products. It can be said to be one of the largest production sectors in the plastics production industry. Plastic processing is developed because of the development of synthetic resins. With the continuous improvement of science and technology, plastics
The processing technology has also been greatly improved. At present, it is mainly composed of the steps of batching, molding, cnc plastic machining, joining, modification, and assembly. Let's take a closer look at its technological process.

Plastic Processing Process

1. Ingredients

This is the first step in the plastic processing technology. In addition to the polymer, it requires the addition of some plastic additives such as stabilizers, plasticizers, colorants, etc., so that the performance of the processed plastic products will be greatly improved. improve, and also reduce production costs. The polymer and additives are mixed together and dispersed as a dry mix. It can also be processed into pellets.

2. Forming

This is the most critical step in the plastic processing process. We need to make various forms of plastic into the desired shape. There are many ways to form this, and the choice is mainly based on the type of plastic, the initial shape, and the size and shape of the product. If it is a thermoplastic, extrusion, injection molding, calendering, blow molding and thermoforming are generally used; if it is a thermosetting plastic, molding, transfer molding, or injection molding can be used. In addition, there are castings using liquid monomers or polymers as raw materials.

3.CNC Plastic Machining

This step can be seen as an auxiliary process of forming. It can borrow the cnc plastic machining methods of metal or wood to manufacture some plastic products with precise dimensions or small quantities. However, the performance of plastic is completely different from that of metal and wood. The tools and cutting speed used in machining must conform to the characteristics of plastic.

4. Joining

This step is to join the plastic parts together. There are two main methods: welding and bonding. The welding methods are mainly hot air welding, hot melt welding, high frequency welding, friction welding, ultrasonic welding, etc. The bonding method is done using adhesives such as flux, resin solution and hot melt adhesive bonding.

5. Modification

The purpose of this step is to beautify the surface of plastic products, generally through mechanical modification, that is, grinding, filing, polishing, etc.; and then finishing, such as coating the surface of the product with paint, covering the surface of the product with a patterned film, etc. ; There are also coloring, such as painting, printing, etc.; there are also metal plating, including vacuum coating, electroplating, and chemical silver plating.

6. Assembly

This is the last step in plastic processing, which is to combine the individual plastic parts processed into a complete plastic product.

Several of the most common plastic processing processes

• Extrusion: Extrusion is also called extrusion in plastic machining and extrusion（Different from aluminum extrusion） in rubber processing. It refers to a processing method in which the material passes through the action between the extruder barrel and the screw, is heated and plasticized, and is pushed forward by the screw, and continuously passes through the head to make various cross-sectional products or semi-products. Extruded products are continuous profiles, such as tubes, rods, wires, plates, films, wire and cable coatings, etc. The extruded products produced by Baoyi use a variety of unused raw materials, among which the most commonly used are cnc machining peek,PC, ABS, PVC, PS, PE, PP, TPE, TPE, TPU, etc. After the processing is completed, there are many plastic products such as LED lampshades, drain pipes, supermarket price tags, etc. that appear in our lives. The processing technology is extrusion.
• Injection Molding: Thermoplastic injection molding, a method in which the plastic material is melted and then injected into the film cavity. Once the molten plastic enters the mold, it is cooled and shaped into a cavity-like shape. Injection-molded products are also very common in our lives. Our most common products are: computer case shells, connectors, mobile phone shells, keyboards, mice, stereos, etc.
• Blow molding: also known as hollow blow molding, a rapidly developing plastic processing method. The tubular plastic parison obtained by extrusion or injection molding of thermoplastic resin is placed in a split mold while it is hot (or heated to a softened state), and compressed air is introduced into the parison immediately after closing the mold to blow the plastic parison. It expands and sticks closely to the inner wall of the mold, and after cooling and demoulding, various hollow products are obtained. The plastic processing technology for bottles, barrels, cans, boxes and all containers for packaging food, beverages, cosmetics, medicines and daily necessities that are common in our lives is blow molding.

The above is the technological process of plastic processing. The most important ones are the first two steps. The latter four processes are carried out after the plastic has been formed into a finished product or semi-finished product, which is regarded as the secondary processing of plastic. In the process of plastic processing, it is inevitable to encounter various problems, among which the plastic processing shrinkage problem is the most common and the most difficult one. Only by minimizing this problem can a higher quality of the product be guaranteed. However, with the continuous improvement of plastic processing technology, it is believed that this problem will be solved in the future.

The Judgment Of God Is Real

In the 1950s a young songwriter wrote these lyrics, “What a day that will be when my Jesus I shall see.” For some people it won’t be a day to rejoice. Why? Because the judgment of God is real. Click on the link below to read this very evangelistic post. This is a post you will want to share. #2Thessalonians #BibleStudy #Devotions #eternity

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What Is The Will Of God For Me

Are you looking for God’s direction for your life? Are ready to GO but the Lord is saying NO! At least, not yet. We must make sure we know the fundamentals of Christianity. Check out today's post by clicking on the link below, you'll be glad you did. #1Thessalonians #BibleStudy #Devotions #GodsPurpose

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What is investment casting？Use a mold to shoot wax to make a wax pattern in the shape of a spare part; then apply it with a refractory material, then heat to remove the wax in the middle; then use it as a mold shell and inject molten metal iron. Wax casting (also called investment casting, lost wax casting). This casting method is extremely cost-effective when used to manufacture products such as complex and three-dimensional shapes.

1) Drawing
First of all, it is necessary to fully discuss various conditions such as the concept, purpose, and size of the product. In order to produce a product that pays attention to product economy and operability, it is necessary to conduct thorough communication and negotiation in all aspects such as shape and material.

2) Mold making
Secondly, the mold making of the forming wax mold is based on the pre-agreed design drawings, and the mold design of the neutron is carried out to improve the efficiency and reduce the cost.

3) Wax mold making
Wax is injected into the mold to make a wax pattern. The shape of this wax mold solidifies into the shape of the casting.

4) Group tree
The wax module of the product is welded to the casting rod and assembled like a branch, this state is called a group tree. Multiple castings can be produced at one time.

5) Shell making
The assembled wax mold is dipped into the slurry (binder), and the surface is coated with refractory material and allowed to dry. This operation is then repeated until it finally reaches a suitable thickness.

6) Dewaxing
The shell is heated with high temperature and high pressure steam, and the wax in the prototype of the product is dissolved and flowed out. The melted part becomes the cavity, which becomes the base of the shell.

7) Roasting
The firing of the shell is to improve the strength of the shell. In addition, it also has the effect of removing impurities in the shell by heat.

8) Casting
Dissolved metal steel water is injected into the fired mold.

9) Vibration shell cleaning
After casting, the outer shell is removed by sand cleaning of the vibrating shell, and the casting containing the casting rod product is taken out.

10) Cutting
The casting of the product is removed by laser cutting from the casting rod, and a prototype of the casting is completed at this stage.

11) Heat treatment
After heat treatment, the mechanical properties of the casting products are adjusted to achieve suitable properties.

12) Check
Inspection of appearance, shape, size, and inspection of casting defects are carried out. In addition, depending on the product, mechanical
Workmanship, surface treatment and other requirements.

13) Packing for delivery

God Gives Grace To The Humble

Both Peter and James included the following statement in their epistles. "God opposes the proud, but He gives grace to the humble." The Lord does something special for us when we are humble before Him. Click on the link below to read about it. #1Peter #BibleStudy #Devotions #Grace

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How Much Does God Love Me?

God’s love is immeasurable because the scripture tells us that God is love. With that in mind, how does His love relate to us? How much does God love you and me? Check out today's post by clicking on the link below. #1John #BibleStudy #Devotions #Evangelism #Love

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That Your Joy May Be Full In The Lord

How can you be sure that your joy may be full? The Apostle John answered that question in the first epistle he wrote. Jesus also gave us insight into having complete joy as well. Click on the link below to read today's post. #1John #BibleStudy #Devotions #joy

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How To Be Free In Life

Happy 4th of July, Independence Day. We celebrate it with picnics and fireworks and other summer activities. But today, as well as with everyday, we can also celebrate our dependence as we lean on our Lord Jesus. Click on the link below to read today's post on how to be free in life. #BibleStudy #Devotions #Romans #sin

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