Mold design calculation

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Mold design calculation

Estimating the amount of material needed for a project can be a difficult task. Not having enough material or having too much left over is not only frustrating, but costly. To assist you with these calculations, we are happy to provide the following tools. Convert the net weight of a material to a linear coverage at a specified thickness. Brush On Mold Estimator Estimate how much material is needed for a brush on mold.

Casting Estimator Estimate how much material is needed to cast into your mold or form. Coating Estimator Estimate how much material is needed to coat a surface with material. Disclaimer Although we do our best to ensure the accuracy of these tools, Smooth-On offers no warranty either expressed or implied as to the reliability of the information contained herein.

Smooth-On assumes no liability for loss or damage associated with use of these calculators. In almost all cases, it is better to have too much material on-hand than not enough. Volume: Area:. Volumetric Yield Convert the net weight of a material to a volume. Linear Coverage Convert the net weight of a material to a linear coverage at a specified thickness.

Important Announcement We are open.How the calculation of mould life? Dear Doberia Generally life cycle is forto 1million shots, if there is spare inserts to replace cycle will increase, some use soft steel for low volume of the parts, this gives lesser cycles. Mold life is decided as per quantum required before a mold is born.

Necessary features are incorporated to give it the required life. SPI classification is available for guidance. I agree with Saravan and Raj. It starts with the grade of tool built hardend tool steel cavity and cores 1 million shot is realistic but the grade of resin is an imporntant factor.

As a rule you get out what you put in pay no or pay later. The above is true, also part geometry and size of the part affects mold life. For example, we have a mold for fishing bobber stems, this mold will last over 10 million parts with some minor maintenance. We have a tray mold with side pockets, this mold requires significant maintenance atparts. Both molds are heat treated.

I agree, but beyond the design of the mold and execution of it. How the mold is run, and maintained feeds into the calculation. I have seen excellent tools torn to bits by poorly run molders, with little or no P. Sometimes you get even less than you pay for in the exchange I will also like to add ,that Machine will also play a role in mold life. A sturdy machine with excellent parallalism of platen will add more life to the mold.

Similarly the precise mold protection can guard it against double shot. I remember a split mold where split used to move from its place while removing artical from mold and used to get damage in next cycle. In short a mold running in Auto cycle on a precision control sturdy machine will give very good life even if it not fully hardened. We have many molds with over 25 million cycles on them, and are still running fully automatic 24 hours per day, 7 days per week.

It does, as Mr. Parsons pointed out, also very much depend on the care and maintenance that the mold receives, and the quality and accuracy of the molding machine that the mold is run in. Other Threads. Get a Price Sitemap.Calculate Plastic Mold Shrinkage Plastic injection molding shrinkage is the contraction of a plastic molded part as it cools after injection. After that, the part may continue to shrink very slightly for several hours or even days until the temperature and moisture content stabilize.

Thus dimensional inspection should wait at least a day. Plastic injection molded part shrinkage units are expressed as thousandths of an inch per linear inch 0. Typical shrink rates vary between 0. When calculating shrinkage, the tooling engineer simply scales the part by 1.

In pre-CAD days, the engineer would expand your part by simply multiplying every number on the drawing by 1. Plastic injection molding shrinkage varies with wall thickness also.

The material supplier will usually provide a range such as 0. If your wall thickness is 0. The molder can fine tune the shrinkage of the parts by adjusting the density of the material, i. Many injection molders have a huge rack of obsolete tools. Find one of these that makes a part somewhat similar in size, shape and wall thickness to your part. Then pay your molder to shoot your resin into it and use the parts to calculate a precise shrinkage for your material.

The cost of doing this is small compared to that of reworking or scrapping a tool. A few plastics shrink differently in one direction than in the other. For example, polymers filled with long glass fibers will shrink more in the cross transverse direction than the longitudinal flow direction. This poses an interesting dilemma for the mold designer. The material supplier will tell you that you have to use a different shrink in the X axis than in the Y.

This is fine if you are making popsicle sticks or rulers. But if your part is complex, like with holes and flow fronts meeting at different angles and running different directions at different places in the part, it is impossible to do, and would be outrageously expensive even if you could. Even round holes would now become elliptical in the tool so that standard components such as core pins cannot be used. What winds up happening is that the average between longitudinal and cross shrinkage is assumed, everybody signs off on it, and then critical features are then altered or added after first shots.

What is clamping force and how do it find in hindi

Calculate Plastic Mold Shrinkage. Calculate Plastic Mold Shrinkage Denny Scher T Calculate Plastic Mold Shrinkage Plastic injection molding shrinkage is the contraction of a plastic molded part as it cools after injection.

Asymmetrical Shrinkage A few plastics shrink differently in one direction than in the other.

[Injection Moulding Calculations] - PDF

The bottom line is, do not use asymmetrical shrinkage resins if close tolerances matter.What is a injection molding? How does it work and what is it used for? In this section, we answer these questions and show you common examples of injection molded parts to help you familiarize yourself with the basic mechanics and applications of the technology.

Injection molding is a manufacturing technology for the mass-production of identical plastic parts with good tolerances. In Injection Molding, polymer granules are first melted and then injected under pressure into a mold, where the liquid plastic cools and solidifies.

The materials used in Injection Molding are thermoplastic polymers that can be colored or filled with other additives. Almost every plastic part around you was manufactured using injection molding: from car parts, to electronic enclosures, and to kitchen appliances. Injection molding is so popular, because of the dramatically low cost per unit when manufacturing high volumes.

Injection molding offers high repeatability and good design flexibility. The main restrictions on Injection Molding usually come down to economics, as high initial investment for the is required. Also, the turn-around time from design to production is slow at least 4 weeks.

Injection molding is widely used today for both consumer products and engineering applications. Almost every plastic item around you was manufactured using injection molding.

But compared to other technologies, the start-up costs of injection molding are relatively high, mainly because custom tooling is needed. All thermoplastic materials can be injection molded.

Some types of silicone and other thermoset resins are also compatible with the injection molding process. The most commonly used materials in injection molding are:. InJohn Wesley Hyatt invented celluloid, the first practical artificial plastic intended to replace ivory for the production of Early injection molding machines used a barrel to heat up the plastic and a plunger to inject it to the mold.

In the mid s, the invention of the reciprocating screw single-handedly revolutionized the plastics industry. The reciprocating screw solved key issues with uneven heating of the plastic that previous systems faced, and opened up new horizons for the mass production of plastic parts.

Recently, the demand of biodegradable materials is increasing for environmental reasons. In this section, we examine the purpose of each of these systems and how their basic operation mechanics affect the end-result of the Injection molding process.

Watch a large injection molding machine in action while producing 72 bottle caps every 3 seconds in the video here:. The purpose of the injection unit is to melt the raw plastic and guide it into the mold. It consists of the hopperthe barreland the reciprocating screw. The mold is like the negative of a photograph: its geometry and surface texture is directly transferred onto the injection molded part.

This is due to the high level of expertise required to design and manufacture a high-quality mold that can produce accurately thousands or hundreds of thousands of parts. Molds are usually CNC machined out of aluminum or tool steel and then finished to the required standard. Apart from the negative of the part, they also have other features, like the runner system that facilitates the flow of the material into the mold, and internal water cooling channels that aid and speed up the cooling of the part.

Learn more about CNC machining. Read the complete engineering guide Recent advances in 3D printing materials have enabled the manufacturing of molds suitable for low-run injection molding parts or less at a fraction of the cost. Such small volumes were economically unviable in the past, due to the very high cost of traditional mold making.

An industrial mold design for producing a tens of thousands of parts number of plastic parts. The cavity is show on the left and the core on the right. The simplest mold is the straight-pull mold. It consist of 2 halves: the cavity the front side and the core the back side. In most cases, straight-pull molds are preferred, as they are simple to design and manufacture, keeping the total cost relatively low.

There are some design restrictions though: the part must have a 2. D geometry on each side and no overhangs i.Learn more about Scribd Membership Home. Read Free For 30 Days.

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mold design calculation

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mold design calculation

Download Now. Related titles. Carousel Previous Carousel Next. Design and manufacturing of plastic injection mould. Jump to Page. Search inside document. If we are running the screw and injection unit at psi hydraulic we would get x The clamp tonnage works to keep the mold closed.

The projected area is only the 2D area of molded part surfaces in the X and Y directions only - do not count sidewall area in the Z direction part depth.

Example: 4 -cavs x The actual pressure varies at each location along the flow length - constantly being reduced by pressure drop in system. More sophisticated mold filling analysis software is needed to accurately quantify the average pressure in mold.

If our equation shows ample tonnage working against full cavity pressure, we know we are conservative which insures success.

Not shown above is one additional system of pressure amplification in the clamp mechanism which generates the tons of clamp force.

As mentioned, tons ispounds. If the typical system hydraulic pressure is psi, we can calculate the clamp cylinder diameter to be This may be too aggressive and can result in molding output deficiencies relative to plan as well as financial losses. Is the coefficient of thermal expansion AT is the temperature change Tics - Tuow L isthe length subjected to the expansion Example: The leader pins on a mold are This 0.

Note also that the shut height of this mold is This will grow to be Note that the mold is located in press by the locating ring which is 3. These locations locations are unaffected by thermal expansion about the mold's center line.

Dante C. Fairos Triady Faisal. Stelwin Fernandez.By its very nature, plastic injection molding is a manufacturing process that creates a lot of pressure. The two halves of the mold are brought together by the injection molding machine, and the molten plastic resin is injected into the mold at high pressure. Clamping force refers to the force applied to a mold by the clamping unit of the injection molding machine.

There are many factors and formulas that go into measuring the force required hold the mold closed. This page covers a high-level explanation of the factors that are considered in determining the clamping force that will be required to injection mold a certain part.

This is a critical determination for the success of the parts — too little clamping force can cause problems, and too much clamping force can cause problems for the parts, mold or machine.

Normally, the injection molding machine clamping force rating is stated in tonnage. A ton machine, for example, is capable of producing a maximum clamping force equivalent to a total of tons.

The clamp tonnage requirement is used to select a capable machine that will prevent part defects, such as excessive flash. The required clamping force can be calculated from the cavity pressure inside the mold and the shot projected area, on which this pressure is acting.

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There are variables that affect the clamping force calculation, such as the surface area of the part, the material type low-flow versus high-flow plasticand the depth of the part. The first step in determining appropriate clamp tonnage is to calculate the surface area of the part.

This simply means getting the square inch area of the cavity by multiplying the length by the width. If it is a multi-cavity mold, multiply the number by the number of cavities. Then any cored-out surface area is subtracted from the area, and the area of a cold runner has to be taken into consideration if the mold has one. Once the surface area is calculated, the area is then multiplied by a tonnage factor.

Typical tonnage factors can range from 2 to 8 tons per square inch, depending on the material. So at this point in our calculations, a ton machine would be a good choice.

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Keep in mind that we need to select the right clamp tonnage machine — too much can cause problems for the parts or machine. Once we have this starting point for calculating the proper clamp tonnage, other factors have to be considered. Since the purpose here is to present a high-level overview of clamp tonnage, we will only discuss melt flow and part dimension.

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After calculating the surface area, the next item that needs to be considered is how the material flows. There is an inverse relationship between viscosity and the MFR.

About Mold Design in Inventor

Materials with a low viscosity have a high melt flow, and therefore require less clamping force. Conversely, materials with a high viscosity have a low melt flow, and require more clamping force. If the depth of the part is greater than 1 inch, we have to factor this into our calculation. This does not refer to the thickness of the wall, but to the total depth of the part. This piece is 4 inches long and 4 inches wide, which gives us 16 square inches.

The multiplier we are using for our material is 5, so we will multiply 16 by 5 and get 80 tons.

mold design calculation

So, we need to add an additional 8 tons for a total of 88 tons. Therefore, we need a machine with a minimum clamp force of tons to mold our part. As previously mentioned, there is a danger in choosing an injection molding machine with too much clamp tonnage. Doing so can cause part defects, mold damage or machine damage. Some typical molding defects that are immediately apparent on parts are burns, gloss level changes and short shots caused by excessive clamping force. Besides the immediate defects on the parts, too much clamp tonnage can also have negative long-term side effects on the mold.

It can cause rolled parting lines, crushed vents, and even break inserts or crack the core or the cavity block.There are many different ways to calculate the an injection mould price, but, they have one thing in common, that is taking efforts to make technical and economic indicators organically combine in order to produce mutual benefits.

It will make the injection mould to have competitive prices from the valuation to offer, to contract and to the settlement price. Materials Coefficient Method Mould material costs can be calculated by mould size and material prices. Injection Mould Quotation Strategies and Settlement Pricing and billing is the continuation and results after injection mould valuation.

Mould quotation and valuation is only the first step, the ultimate goal is the final settlement price of the mould after manufacturing and delivery.

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In practice, this is not exactly equal to the valence. There may be fluctuations in the value of the error. That is the question to be discussed below. After the injection mould valuation, the offer needs to be organized into a mould processing contracts signed as basis.

Through repeated negotiations, both sides approved the final form of the mould price, signed a contract. Then finally start plastic injection mould making. Mould Valuation, Quotation and Pricing The mold valuation cannot be the direct quotation immediately. After bargaining, the price can be reduced according to the actual situation.

Mould prices are approved and signed by both parties in the contract price.

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In this case, the mold price may be higher or lower than the estimate. When the price is lower than the guaranteed, the injection mould needs to be re-amending the requirements, conditions, and other programs to reduce some of the requirements, in order to reduce the cost.

mold design calculation

After re-estimating, a contract price can be signed. It should be noted that the mould is high-tech specialty products, should not use low-cost, or even at a loss to cater to customers. But, it should be done at competitive prices, the quality assurance, precision, life in the first place, rather than the price.

Injection Capacity Calculator

The pursuit of low-cost mould, it is difficult to ensure the injection mould quality, accuracy and service life. However, when the plastic injection mould manufacturer is the same or has an economic interest in the relationship, in this case, the offer should be cost price quote.

Die valuation estimate only the basic cost of the mould, the other costs and profits will not consider being products of the future profits. But this time the offer is not as true mould of the price, can only be used as a mold pre-development costs. In the future, once the products successfully developed, generate profits, should die for extracting value, the unit returned to the mould manufacturing, the two together to form a mould price.

In this case the price of the mould is formed, there is likely to be higher than the price of a first mould case, even a high rate of return, is several times the original price of a normal injection mould, a few hundred dollars.

Of course, there may be the rate of return equal to zero. The Regional and Time Differences of Mould Price It should also be noted that injection mould valuation and price can be different in various enterprise, region and national, as well as different time and environment. That is, there are regional differences and time difference. The reason is: on the one hand enterprises, regions, countries manufacturing conditions are not the same, different equipment, process, technology, personnel concepts, standards and other aspects of consumption, resulting in costs of the injection mold, estimated profit targets different, resulting in a different mould price difference.


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