Weld line, also known as knit line or meld line, is a visible line or mark on the surface of a plastic part where two or more flow fronts of molten plastic meet and fuse together. com TYPICAL PROPERTIES MECHANICAL THERMAL OPTICAL. The thickness of the part plays an important role in how difficult the molding process will be. Injection Pressure 0r Speed Too Low Explanation: If the injection speed or pressure is too low, the molten plastic will not be pushed into the mold cavity fast enough to fill and knit at converging flow fronts because it cools down and solidifies too soon. Be wary of saving too much weight or you might end up with: cracking. Injection Molding Guide. Parting lines placed at intricate joints. the thin blades. 3,000 ton machines can cost $700,000. Common causes of flashing in injection moulding. The influence of knit-lines on the tensile properties of injection molded parts. 3 /sec of material into a mold, don’t think the material is going into each cavity of a multi-cavity mold at the same 14. Holes in plastic parts are normally cut with a router (or drilled if round. Learn Injection Molding Glossary with Plastopia: Using actual molded parts (with images) as examples. The cracking was always located in the weld/knit line and therefore caused by weakness in the bonding of the plastic at that line. As a result, prototyping is strongly recommended for parts with. Three terms that often get mixed up are weld, meld, and knit lines. The plastics used by injection molding processes are relatively cheap and can be used to achieve a wide variety of properties, so injection molding is popular for creating many packaging and consumer products, like LEGO! A weld line (weld point, flow line or a knit line) forms when separate melt fronts travelling in opposite directions meet. ISO 9001:2015. Expand. Considerations: ABS-molded parts will show. The injection molding machine includes a fluid path extending through the first mold portion. Venting is required to allow the air in the sprue, runner and cavity to leave the tool as the melt flows into the cavity. The diameter of the secondary runner would be the diameter of the tertiary runner times the number of branches to the 1/3 power (cube root). Examples of different causes of PVC pipe failure. May happen at first shots while mold is being dialed in. ABS (Acrylonitrile Butadiene Styrene) Benefits: ABS is a tough, impact-resistant plastic that is widely used across many different industries. 45 in. While injection molding itself is a straightforward process involving melting thermoplastic resin and injecting it into a mold cavity, knit lines can pose. The parting line location on the injection mold will have an effect on how the cavity and core (both halves of the injection mold) come together and seal. In injection molded parts, there are 2 types of weld lines: The first type of weld mark is called cold-melt joints and is formed when the melt front enters the cavity with different gates. This production method is particularly popular when manufacturing in large quantities. Solution: People. Our Injection Molding Capabilities • Horizontal Injection Molding up to 3300 TONS • Structural Foam Molding + Structural Web • 1oz to 600oz part capacity. The plastic melt that passes through the gate at high speed directly enters the cavity, then contacts the surface of the cavity to solidify, and then is pushed by the subsequent plastic melt, leaving traces of meandering. This production method is particularly popular when manufacturing in large quantities. Once the plastic cools, the mold is removed, and the object is ready for post-processing. Getting started; Knit Line Injection Molding; Knit Line Injection Molding - China Manufacturers, Factory, Suppliers. Comprehensive. The parting lines is where the two injection mold halves (A side and B side) meet. Knit Lines. You don't give us much to go on. Since our material is injected through a. In fact, strength at the knit line can be as little as 20 percent of the nominal strength of the part. 120 in. Islyn Thomas summarized the need for a particular vent location better than I ever could. 3. In fact, knit line strength will decrease with higher filler content and with longer fibers. Overall, injection molding is a relatively simple process. Recommended for the bonding of nylon (polyamide) and polypropylene materials, this thermoplastic elastomer delivers wide compatibility and thermal stability, allowing for use in demanding conditions. Improve venting and/or relocate to burned area. Brent Strong, p. 1. Knit lines don’t. Weld lines or knit lines and meld lines formed when two melt fronts run into each other or join together can be improved by. "As soon as that part or material is stressed, it can be real conducive to fracture, cracking, breaking, just because of the way it's been molded. Swirling can increase depending on the material you use, and the texture or polish of injection molding tools. Plastic injection molding has long been an affordable and efficient process for producing custom prototypes and end-use production parts. Gates, vents, sliding cams, pick-out inserts, and any other place where the two sides of. There are times when porous materials like Porcerax are used in problem or backfill areas. Therefore, with the cooling process, the resin in the central part shrinks and expands to the surface, resulting in insufficient filling in the central part, which is called vacuum. The knit lines are the result of poor molding conditions (likely molding at too low of a temperature). A poor knit line can cause cosmetic blemishes and significantly weaken the structural integrity of a part. 1 in. He is currently a tooling manager for a large, multi-plant molding and manufacturing company. Additionally. The Problems & Solutions course is designed to train injection molding personnel in. Knit lines, also known as weld lines, are fine lines that resemble hairline fractures or cracks. Double push filling method. Plastic melt and mold temperature. injection molding. suppressed cooling and possibly warp. doc), PDF File (. . Learn more. 8 mm (32 threads per inch) Use a trapezoidal or buttress thread. A knit line in a plastic injection-molded part is created when two separate plastic flows meet within the mold and "resolidify" along their interface. The weld line can either be a minor cosmetic issue. This article will discuss the importance of injection molding nozzles and what makes a good nozzle for a molding or injection. I am working on a thin PC/ASA injection moulded component which has a tendency to snap at the Knit-point (the final point of travel at which the…Here are a few of the most common defects that may occur in plastic injection molding — and how product teams can avoid them. To ensure quality parts, injection molding companies must have the best injection mold design first + (91) 96067-70777 +(971) 547-161-112. POROUS MOLD MATERIALS. Take these steps to avoid knit lines. These knit lines affect the parts aesthetics. Revisiting the '5 M's' of Molding. All the while, the material could be the correct material," Hill says. One of these is knit lines, also called weld lines. ABOUT THE AUTHOR. A component of the injection-molding machine wherein the resin pellets are melted, compressed and injected into the mold's runner system. An injection mold that produces pieces while the final tool is being built. Edge gates, which can include fan and tab-shaped gates, are the most common ways to gate a tool. com. POROUS MOLD MATERIALS. Since the intention is to preserve fiber length in LFRTs by reducing. He is currently a tooling manager for a large, multi-plant molding and manufacturing company. The injection molding process offers a vast array of plastic resins to work with. Injection moulding is a manufacturing process that melts, injects and sets plastic into a metal mould. Transfer molding also utilizes a press and a mold. In the injection molding process, knit lines are a common occurrence when two or more plastic flow fronts collide and solidify, resulting in a visible seam or line on the molded part. Weld line are formed whenever melt fronts separate and recombine at some downstream location. A knit line may only be a cosmetic issue and affect. When setting a heat profile, consider residence time, screw RPM and filler type. Causes: Weld lines are caused by the inadequate bonding of two or more flow fronts when there is partial solidification of the molten plastic. The uneven thickness of the product will make the melt flow resistance larger and smaller, resulting in unstable melt flow. Part Design Summary Bosses:Welds and/or Knit lines can be defined as the inability of two or more flow fronts to “knit” together, or "weld", during the molding process. incomplete filling or shorts. This information is intended to be used only as a guideline for designers and processors of modified thermoplastics for injection molding. Figure 1: Knit lines in a cover plate. Obstructions in the part create weld lines or knit lines during injection molding. a knit line will form 180°on the opposite side from the gate location. Causes 1. Adding draft or slope to vertical walls of a part makes it easier to eject or remove the part from the mold. 08 KICKOFF PRODUCTION. For those processes in which the plastic fills out a mold (cold press, compression, injection, reaction injection, resin transfer, structural foam, and transfer molding ), openings in the part can be molded into the part through the use of cores. When the mold adopts the multi-gate pouring scheme, the plastic melt. Long shapes are produced without multiple drops or hot runner systems, eliminating knit lines and lowering tooling costs. Knit Line Injection Molding is a process that allows manufacturers to produce parts more quickly, accurately, and at less cost than traditional injection. On a hydraulic machine you can program hold pressure: For example, if you set 850 psi (59 bar), you will get 850 psi hold pressure for the time you set on. plastic recycling machine, blown film extruder, filament extrusion line, injection molding machine, blow molding machine, injection blow molding machine, bag making machine, flexo. An edge gate introduces material at the main parting line, or where the two halves of the mold meet, with a perpendicular runner. Randy Kerkstra has been in the plastics industry for over 26 years, occupied frequently with troubleshooting injection molding. For the production of these weld‐line specimens, a special mold was used and injection molding parameters were systematically varied, tensile (ISO 527‐2) and impact (ISO 179‐1/1eU. These knit-lines are well-known as particularly critical regions in the mold when mechanically. Weld lines typically appear in a part when an obstruction of some kind separates the melt flow and prevents it from "knitting" together. To briefly describe, weld lines are also called knit lines. The goal is to create a uniform thickness and at the smallest (thinnest) level required. The injection molding process uses a granular plastic that is grav ity fed from a hopper. A weld line, or knit line, occurs when two flows of melted plastic meet and “knit” together. Injection molding machine and automation supplier Engel offers an array of technologies to simplify and speed up mold changes, including magnetic clamping platens and quick couplings; intelligent assistance systems; and the famox mold changing system for automating the set-up process. An injection molding machine having a first mold portion and a second mold portion. They occur when two resin flows meet at different. plastic recycling machine, blown film extruder, filament extrusion line, injection molding machine, blow molding machine, injection blow molding machine, bag making machine, flexo. Our plastic injection molding glossary provides key terms. 3. Increasing injection speed. Remedies: Raise the temperature of the mold or molten plastic. Weld / Knit Lines; Assumptions. Consider adding mold release (can be added to the polymer itself by the polymer vendor) or at machine side Knit lines Weak knit lines Increase melt temperature Mold temperature too cold Increase injection speed Avoid nucleated products if possible Inadequate ventingWhat you should know is that there are various failure modes for injection molding. For injection molding of the multi-blade fans and various rotating plastic parts, the complex of multiple gating injection molding tools were used. Change gate locations. Design. By using this method, theHowever, injection molding is not without its challenges. 5 mm (0. With over 50 years of experience, Universal Plastic Mold can help you avoid (or at least minimize) knit lines in your molded parts. Piccarolo, S. Weld lines typically appear in a part when an obstruction of some kind separates the melt flow and prevents it from "knitting" together. Depending on the design of the mold and the material being injected, a knit line may: present no problem at all, be a cosmetic issue, or cause a potentially serious structural problem. For. Strength at the knit line can be as little as 20% of the. Based on the resin. A weld line refers to a line, notch or color change that is created on the molded part caused by the convergence of two separate flows of molten plastic. 2) Vents in an injection mold should let the air out, but not the liquid plastic. These lines occurs usually around holes or obstructions and cause locally weak areas in the molded part. The runner and gate system used in plastic injection molding is responsible for directing molten plastic from the nozzle of the molding machine into the cavity of the tool. Edge Gates. spelling: injection molding) is a process for producing parts by injecting molten material into a mould, or mold. Learn more. Bead Blasting. This slight depression is a tiny line called the weld line or knit line. Quotes for 25+ Manufacturing Processes. Plastic injection molding has long been an affordable and efficient process for producing custom prototypes and end-use production parts. Weld lines often leave witness marks in the moulding surface. When injection molding complex parts, often knit-lines are formed during the mold filling stage. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. The mold settings can run flawlessly until employees consistently open the machine for inspections, interrupt cycle times, or cause temperature. Knit lines are consideredmolding defects, and occur when the mold or/and materialtemperaturesare set too low:. Depending on the design of the mold. There are times when porous materials like Porcerax are used in problem or backfill areas. Knit line / Meld line / Transfer line Discoloured line where two flow fronts meet Mould or material temperatures set too low (the material is cold when they meet, so they don't bond). TWIM=Thin Wall Injection Molding; TSL=Toys,Sports and Leisure; NB=No Break; IMR=Inter Material Replacement. Raising the mold temperature will keep the material molten longer, resulting in stronger weld lines and even elimination of weld lines. Setting that Delta P is the secret to consistent fill time. And the lead-time for overmolded and insert molded parts is 15 days, a bit longer than FacFox’ single-part injection molding turnaround, but still much faster than traditional insert molding. This course outlines mold filling and how different gating configurations affect filling. This picture shows a. (1987). Plastic injection force exceeding the clamping pressure of the press. This range can be affected by the part wall thickness, melt temperature, mold temperature, injection speed, hold/pack pressures and also the time between molding and measuring. Finally, knit lines occur when molten plastic flows around an object and rejoins on the far side, a phenomenon that is quite possible when inserts. Polypropylene can be processed over a wide range of mold temperatures; however, for applications where aesthetics are critical, a surface temperature of 80-95˚CSink Marks Cause 1: Incorrect Melt Temperature. Plastics Injection Molding Expert John Bozzelli covers. Compression molding produces solid parts that are free of flow and knit lines. 5 mm) is ideal, according to injection molding engineer Jack Rulander of Protolabs in Maple Plain, MN. Bad habits can cause many different problems with injection molding machines, and flow lines are included in that. Weld-line is a defect that arises in injection molding when two or more flow fronts collide. weld line in injection molding. Also known as a knit line, this is the point at which two flow formations meet and are unable to. Injection molding can be a real challenge if you don’t follow the “Five M’s”: Man, Mold, Machine, Material and Method. Steven. Weld lines occur where two flow fronts meet and always provide a source of weakness as the two fronts do not knit together. Knit lines, weld lines, mold lines, or flow lines in injection molding are faint lines that become visible on certain plastic parts. If the load is applied in the transverse direction relative to the knit line, matrix cracking is easily initiated, and the part can fail. Knit Lines. Knit lines don’t always compromise the structural integrity of plastic parts. suppressed cooling and possibly warp. Three terms that often get mixed up are weld, meld, and knit lines. In places where the plastic flows around a solid piece of the mold, from a simple circle to forming complex shapes like rings or squares. 1016/0254-0584(86)90019-2 Corpus ID: 136712450; Impact strength of knit-lines in injection moulded parts @article{Criens1986ImpactSO, title={Impact strength of knit-lines in injection moulded parts}, author={R. อุณหภูมิของพลาสติกเหลวสูงเกินไปจนก๊าซหรือความชื้นแยกตัวออกมาได้. More about the knit lines in injection molding. Knit lines and other aesthetic characteristics of the part are strictly related to the plastic’s temperature during molding, so efficient filling time is essential for achieving proper welding lines and quality parts. If you turn on the spigot to a garden hose, you will hear a hissing sound at the nozzle end for the first few seconds. To study the weld line formation of colliding flow fronts the filling of a mold cavity was simulated. Islyn Thomas summarized the need for a particular vent location better than I ever could. Short shots Trapped air in the mold can inhibit the flow of the material during injection, resulting in an incomplete part. Weld Lines. All injection molding ultimately comes down to the “Man, Mold, Machine, Material and Method. Factors within the tooling can also contribute to flow and knit lines, calling for mold modifications. 040 and 0. What causes knit lines? Knit lines are formed when the molten plastic flowing into the mold cavity runs into an obstruction, such as a core pin that forms the through hole on a flange of an enclosure. Solution: Increase the injection pressure or speed. Wavy lines are another feature of weld lines. 0035"Weld lines:Witness line where 2 or more fronts of molten plastic converge, also called knit lines or flow lines, the weld around the holes, the line between the injection gate. Behind the obstruction, the flows try to merge again, but this is made more difficult by a low temperature of the mold surface and a low melt pressure. . SPI surface finishes are the most common set of injection molding finishing standards around the world with over 12 different grades. Obstructions in the part create weld lines or knit lines during injection molding. Solution: People. Remove holes if possible. In this paper, two different injection molding tests were completed. Polypropylene Consumer and Injection Molding Containers, Crates, Garden Furniture, Housewares, Luggage, TSL, TWIM lyondellbasell. Weld line defects – also known as knit lines – is a defect that occurs when the injected plastic meets within a mold. The process parameters were fixed as follows: Packing pressure of 40 MPa, injection time of 2. A knit line is any line, visible or not, where two resin flows meet. Compression molded parts can vary in thickness without issue. Solution: Increase the injection pressure or speed. A thermoset injection molding process may save as much as 50% of machine time per shot with a faster cycle time compared to a thermoset compression molding process, allowing molders to produce high quantities of thermoset components per day in multi-cavity tools. Description: Flow lines are streaks, patterns, or lines - commonly off-toned in color - that show up on the prototype part as a consequence of the physical path and cooling profile of the molten plastic as it flows into the injection mold tooling cavity. A meld line occurs when two moving melt fronts converge and flow parallel to each other. A poor knit line can cause only cosmetic blemishes or it can significantly weaken the structural integrity of a part. Reducing the dimensions of the runner system. The above guidelines for initial heater band settings are for most injection molded parts. What causes knit lines? Knit lines are formed when the molten plastic flowing into the mold cavity runs into an obstruction, such as a core pin that forms the through hole on a flange of an enclosure. Crossref. Weld lines are a common imperfection to be found in most plastic injected molded parts. Knit line strength is improved since. 6. Plasti-Co. 120 in. There needs to be a balance between fit of the halves, function of the part, visual quality expectations, and the cost to produce the mold. Knit Lines and Resins A knit line is any line, visible or not, where two resin flows meet (see Figure 2). When 2 flows meet, small hair-like discolorations may develop. In injection molding, it is often important to maintain consistent color throughout the part. In fact, knit line strength will decrease with higher filler content and with longer fibers. Bad habits can cause many different problems with injection molding machines, and flow lines are included in that. Add a 0. Having uniform wall thicknesses between 0. The relationship between processing conditions, morphological structure and mechanical properties of knit lines of an injection molded semi-crystalline thermoplastic. In the 1947 book, Injection Molding of Plastics, the late Dr. (1. Knit lines are a common defect in injection molding that can affect the appearance and performance of plastic parts. 060 and 0. In places where the plastic flows around a solid piece of the mold, from a simple circle to forming complex shapes like rings or squares. The process involves feeding the material into a press, where it is cooled or heated as per. The knit lines are the result of poor molding conditions (likely molding at too low of a temperature). M. Weld or knit lines are perhaps the most common and difficult injection molding defect to eliminate. The cooler flow fronts of the resin aren’t forced into the mold surface texture as well as the hotter resin behind the flow front. With the right nozzle, you can boost cycle. 4. A weld line can also be called a knit line. In fact, for a 32-cavity mold, the flow rate in this example drops down to 0. . Table 2 lists the<br /> properties of common tool steels and the typical mold components for which they are<br /> used. Viscosity represents a broad concept with huge effects on any efforts to standardize an injection molding process. Knit and Meld lines are inherent to plastic injection. Injection molding is the most cost-competitive technology for manufacturing high volumes of identical plastic parts. This image shows a PVC pipe after it was accidentally dropped on the ground. lines are formed when there is an obstacle in the cavity of the injection mold. A. Having a basic understanding of the injection molding process will aid in understanding how to design for injection molding as well as how to forecast production schedules. From the start of your project, you can count on The Toolroom to exceed your expectations for all of your plastic injection molding needs. An option to bluing agents, the long established means of gauging pressure distribution, comes via Pressurex, a thin, flexible, plastic film. This article looks at the issues presented by a weld line in injection molding and the techniques manufacturers can use to avoid them. The Fusion of Weld Lines. Additionally, it may produce sinks and voids caused by localized shrinkage during the part’s cooling process. PROBLEM: POOR ADHESION OF LSR MATERIAL TO. Plastic injection molding has long been an affordable and efficient process for producing custom prototypes and end-use production parts. Poor venting. Weld or knit lines are perhaps the most common and difficult injection molding defect to eliminate. A structural finite element analysis (FEA) can be used to compare locations of high stress to the locations of the knit lines identified in the mold-filling analysis. These knit lines affect the parts aesthetics, but also they generally decrease the strength. These knit lines are usually the weakest areas of the part. As the polymer resin is injected into a mold, it flows through all parts of the mold. While mold-filling simulation is a very common tool for predicting the fill patterns of an injection mold, in our judgment there is not yet a commercially available, satisfactory filling simulation for microcellular foam molding. Flow rate and flow speed are cut in half at every runner branch. A weld line refers to a line, notch or color change that is created on the molded part caused by the convergence of two separate flows of molten plastic. S. Learn about the key characteristics of common injection molding materials, recommended applications, and how common thermoplastics compare to one another. Three terms that often get mixed up in the plastic injection molding industry are weld, meld, and knit lines. These knit-lines are well-known as particularly critical regions in the mold when mechanically loaded. The gate is the entry point to the part-forming cavity, where plastic material is injected from the molding machine barrel, through the sprue and runner, into the mold. The area generally has lower strength than the other areas of the part. If the part design’s wall thickness is constant, the magnitude of the plastic’s velocity will be the same at every. Polym. 197 in. 2. In fact, knit line strength will decrease with higher filler content and with longer fibers. It has low shrink and high dimensional stability, and it has good resistance to acids and bases. Specifically, by having a single, continuous injection outlet 140, molding material can be uniformly distributed throughout mold cavity 120 quickly and consistently without resulting in undesirable molding seams or knit lines. 2. And like all manufacturing industries, plastic injection molding lines are more profitable the shorter the cycle time — so long as they produce quality parts. Bubbles are caused by melting flow fronts colliding in a mold cavity. As the melted plastic fills the mold, there are locations where the molten plastic flow stream separates and then comes back together. For non-reinforced or non-filled nylon, the mechanical performance in the knit lines (planes) areas are approximately equal to the mechanical performance of the resin (polyamide) used. Example of a gate location in a finished part Example of knit lines in a finished part. Disadvantage: May rust if improperly stored. Reduction of sink can possibly be had by switching to an ABS/PC-blended material. Weld or knit lines occur when melt flow fronts collide in a mold cavity. A majority of these investigations concern amorphous polymers, whereas a number of engineering polymers are semicrystalline and also contain reinforcing fillers and fibers. Injection molding is the process of injecting liquid thermoplastic into a mold. In the plastic injection moulding industry, we work with materials that are by-products of oil refinement and moulds made of metal casting, so our terminology is bound to be at least slightly confusing. Download : Download full-size image; 3. Poor Knit Lines. Depending on the design of the mold and the material being injected, a knit line may: present no problem at all,. When injection molding complex parts, often knit-lines are formed during the mold filling stage. Anisotropy. Conclusion The formation of weld lines in micro injection molding of plastic depends on different parameters such as melt temperature, injection pressure and fabrication method. Injection moulding (U. 1 in. This line does not normally impact the overall shape or dimensions of the item. Gate design is another critical piece of part function in plastic injection molding. Knit lines, also known as weld lines or meld lines, are visible lines or seams that appear on a molded part where two or more flow fronts meet during the. Knit line / Meld. Melt temperature does. This month, we covered an array of topics including injection mold venting, business strategies and runnerless micro molds. Injection speed and pressure. For this study, a special injection mold was designed and constructed (Figure 1) in order to produce specimens of various thicknesses (from 2 to 6 mm). The recommended minimum production volume for injection molding is 500 units. Increase size of the vents. Mold Flow Analysis computer. These are imperfections in the part where separated flows of cooling material meet and. One of the common defects that can occur in injection molded parts is weld line. Check the diameter of the ejector pins and the pin hole tolerances, if the tolerance is too wide this could allow molten plastic to flow down between the pin and hole surface. Plastic Injection Molding Part Design Guidelines, Plastic part Design Guidance, Parting Line Draft Undercuts Wall Thickness & Uniformity Bosses Gussets and Ribs Radii and Corners Material Shrinkage Gating Ventings Knit/Weld Lines. Rynite® PET is usually processed with melt temperatures between 280 to 285 °C (535 to 545 °F) . Mold vents should function the same way. Injection speed and pressure. An injection mold that produces pieces while the final tool is being built. Knit Lines: These occur when different flow fronts come together as plastic flows through the part cavities. Achieving a high-quality surface finish can be challenging, and other methods, such as polishing or coating, may be required. Weld lines may appear like seams or scratches,. Increase injection speed and pressure: Faster-moving materials will meet more quickly so one doesn’t cool too soon. PVC pipes are manufactured by an extrusion process. Venting. The mold maker may think that some minor defects are acceptable, or they may not even consider them from the beginning, which can cause problems when the injection mold is being manufactured. Knit lines form when two or more plastic flow fronts collide and solidify or “knit” during the molding process. A thermoplastic resin is heated to its melting point and injected into the cavity of an injection mold to produce a specific part geometry. Gas trapping/ poor venting. A weld line (weld point, flow line or a knit line) forms when separate melt fronts travelling in opposite directions meet. Prevent Flow and Knit Lines Through Mold Adjustments. For over four decades, our experienced team and leading edge technology have provided you with tooling solutions from start to finish. The melt is forced to split up during filling of the cavity. Holes in the part will always cause knit lines. The plastic in the ‘flow front’ cannot pass through the core pin, so it flows around the core pin splitting into 2 distinct flow fronts. On average, larger injection molding machinery can cost from $50,000-$200,000 or more. Thanks to the low air counter pressure in the cavity, this allows injection parameters to be managed in a larger window, optimizing injection time, part aesthetics and mechanical characteristics. There are times when porous materials like Porcerax are used in problem or backfill areas.