Category Archives: plastic mold company

The Very Best Tips for Investing Crate Mold with Less demanding

The Very Best Tips for Investing Injection Mold Less demanding

It could be hard to shop for a vegetable crate mold, as there could be a great deal of discussion between end user and seller before the completed vegetable crate mold is settled on. Nevertheless, the few suggestions here can assist save you a lot of time, and ensure the whole course somewhat less complicated.

Make an RFQ that incorporates a lot of specifics.As experienced as moldmakers have proven to be, they will not manage to guess what you is thinking when it concerns what you are in search of. Involve as much details as it is possible to at this stage, which involves the volume of cavities, the chemical substance, the most well-liked lifetime on your vegetable crate mold, as well as whatever promises which you may need. Once you are not too convinced on these concepts, then you should convey to your supplier, and they will make an effort to make it easier to settle on the points is befitting for your wants. The more exact you create the RFQ, the more correct a rate you will receive in return.
Be honest with regards to the reason you need a rate. If you solely want a general cost to pass away to some other unit, after that let the moldmaker understand- then they probably reply efficiently. Setting up an appropriate quotation can take a lot of time, and it is far from good to waste the moldmaker’s hours any time you don’t wish that extensive detail, or if you might not order from them.
Don not offend a provider’s original constructive idea. The information and advice available from your moldmaker remain their right- you can not only bring these suggestions to someone else to accomplish it for your company. If you determine a new moldmaker, therefore undertake their suggestions on board- not merely is choosing another company ideas not really understandable, nevertheless it might also baffle a final moldmaker, who exactly may not realize exactly why those options were prepared at the start.
Take into consideration forming a collaboration with your vendor. Through working tightly with your moldmaker on the subject of charges, plans, and part amount presumptions, you may perform the duties of a crew to reach better outcomes in the end.
Keep on straight dialogue with your dealer through the entire process. A lot of moldmakers will be glad to furnish consistent enhancement files, and keep you updated on the very latest advances for your mold. It is critical that you learn things are moving to timetable, so in case you require some info, make sure you seek so you can ease.
Make sure you forever pay in time. Many moldmakers get the job done to a little spending, and require fees to get paid out before they’re now able to go forward with your mod build. If you happen to postpone making payments, then you definately will not receive your mold on the dot- it is as simple as that. Different moldmakers have diverse settlement policies, therefore discuss with them to figure out an approach that works out for you both.

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Modifying your item model will likely imply changing the mold on its own. Once you end up making changes to your piece design while the mold is now being constructed, you will probably be impossible to receive the mold at the charge quoted, or to the very first timeframe. Every changes indicates the mold ought to be adjusted consequently, which adds to both the cost and the time of the mold create.
Know in ahead of time when your mold will be .There are numerous classifications for a finalization date- they could differ from when the eventual settlement is completed, to any time you are given a trial piece, to shipment of the eventual product. In most cases, a mold may be known as completed after it is well prepared to create the part it is actually intended for. Nearly all moldmakers will be in a position to bring about small alterations to make a component based on print specifications. If these specifications modify late, then the mold should still be looked at as complete- any other alters will have to be paid out .
If a service is very low priced, there is frequently cause hiden. While there will be vegetable crate mold, makers these days who present you with a cheaper-than-average cost for the very good product or service, there will be lots of some others who supply reductions mainly because they cut costs . Eventually, it is better to pay out good money to obtain a high-quality item, instead of having a awful mold that doesn’t satisfy your demands.
When buying a mold, that medieval proverb is definitely correct- you get what you pay for. Every made items that you intend to manufacture is only as nice as the mold which you earlier develop them, which means you have to maintain your mold is flawlessly suited to your needs- prior to buying it.

cap mould machining way-Shaper and planer

There are some plastic cap mould making ways as follows:

PLANING

PLANING

The metal-removing process of planing takes place when the cutting tool moves by a straight back-and-forth motion with respect to the work, or when the workpiece moves in a straight back-and-forth motion with respect to the tool, which is stationary.

Four types of machine tools operate according to one or the other or both of the above principles: the planer, the shaper, the slotter or vertical shaper, and the broaching machine.

SHAPER

In shaping, the tool is reciprocated and the feed of the steel for  cap mould manufacturing  is represented by the width of the cut. Shaping is particularly suited for small work in view of the design and construction of most shaping machines. (It is seldom used to machine work more than two feet square.) Shaping entails producing flat surfaces in horizontal, vertical, and angular planes. In addition, internal surfaces and odd-shaped surfaces can be shaped.

The work is usually clamped in a vise fastened to the table. The typical toolroom shaper has a universal table that can be tilted to 15° and swiveled through an arc of 180°.

Because of its flexibility, the shaper is considered a basic machine tool. It is widely used as a toolroom and die shop facility and, in view of the rate of metal removal, is of limited use in large production runs.

VERTICAL SHAPER

The vertical shaper, commonly known as a slotter, is similar to the shaper except that the ram is reciprocated in a vertical slide. The stroke range in vertical shapers is from 6 to 36 inches. For shaping clearance, the ram may be adjusted to move at an angle to the vertical.

Circular tables for holding the work are usually standard equipment with the vertical shaper. Round shapes can be generated by rotating the table by power feed; however, this is usually not the most economical technique for producing circular shapes.The vertical shaper is used primarily for slotting or key-seating operations.

PLANER

VERTICAL SHAPER

The planer is used primarily in the machining of flat surfaces, where the magnitude of the work is such that it is impractical to machine on a shaper or milling machine.

The planer has a long horizontal bed upon which the work-holding table slides with a reciprocating motion. Above the work table, the tool head (or heads) is mounted on a horizontal crossrail. The tool head is mounted on a slide to permit vertical adjustment so as to set the cutting tool to the correct depth. The crossrail may be adjusted vertically in order to accommodate various sizes of work.

APPLICATION OF THE PLANER AND SHAPER

As mentioned previously, the shaper finds most application in the plastic cap mould shop. It is usually more economical to use a shaper rather than a planer for small work because:

  1.    It is faster and more simple to operate.
  2.    It is a less expensive piece of equipment and uses less power.

The planer is adapted for machining flat surfaces on large work. Similar to the shaper and the milling machine, vertical, angular, and horizontal surfaces can be cut. Work should be routed to a planer if:

  1.    Heavy cuts are required on large flat surfaces.
  2.    The material to be cut is relatively hard (large steel castings).
  3.    Accurate finish is required in such work as slides and guides.

SHAPER AND PLANER CUTTING TOOLS

Shaper and planer tools are similar except for size, the planer tools being considerably larger in order to accommodate the larger work.

Because of the intermittent cutting action of both the planer and shaper tool, toughness is an important criteria in tool-material selection. Consequently, high-speed steel is most commonly used; However, carbide-tipped tools are used for taking light or finishing cuts. It is important that the depth of cut, even when using carbides, be greater than 0.010 inch so as to get a cutting rather than a rubbing action.

The front clearance angle should be about 4° so as to prevent rubbing of the back of the tool on the work. A side clearance of 3° is usually considered adequate. In the cutting of mild steel, a 12 to 15° side rake is advocated. For cast iron where less shearing action is needed, 3° side rake is recommended. The back rake varies from 0° for roughing cuts to about 2° for finishing cuts. With these small rake and clearance angles, the tool is more able to withstand the force of impact at the beginning of each cutting stroke.

reaming

REAMING

 

Reamers are tools used for enlarging and finishing diameters of holes to accurate dimensions . A rose reamer cuts on the end and has a chamfer of about 45° on the edge to aid in entering the hole. The fluted chucking reamer, which does more accurate work, is tapered slightly on the end to aid in entering the hole and it cuts on this tapered surface. In general, the reamer follows the hole being reamed. It will change the direction of a hole only slightly. A reamer performs best as a sizing tool when driven by a floating holder that permits it to follow the hole as the reamer is driven through. There are many types of reamers, with straight or spiral flutes, expanding and adjustable blades. They are made to cut different materials, and designed to cut both taper and straight holes.

provision should be made for the reamer to pass through the hole. Blind holes are difficult to ream, and should be undercut at the bottom on the reamed surface.

When a designer specifies a reamed hole it means that:

  1. A drilled hole must be made accurate as to size.
  2. It requires a drill bushing which is removable (known as a slip bushing), and sometimes a reaming bushing added.
  3. The reamer must be available to provide the size in the particular material; and must be able to fit the machine tool.
  4. Gages (usually plug type) must be available to check the hole, for both operator and inspector.
  5. Duplicate sets of reamers should be available, because production must not be delayed when reamers wear and require sharpening.
  6. Wear on the flutes reduces the diameter of the reamer. When the diameter is below the tolerance required, the reamer may be either scrapped or salvaged by grinding for use on smaller diameter holes.


The designer should standardize reamed hole sizes. Hole sizes are based on mating part dimensions.

It is economical to make pins and shafts from cold-rolled and ground stock in order to reduce the amount of turning and grinding to size. Since this material comes in sizes which are to size or under, a series of reamers should be standardized which will ream holes ±0.002 inch or, according to the designers preference for clearance between shaft or pin and hole.

Whenever a surface must be turned or ground on a pin or shaft, the size should be specified so as to offer the proper fit for a standard-sized reamer, ±0.0005 inch. The oversize reamers cost more than standard-sized reamers, but when they wear they can be ground to a standard size, and thus have a double life.

Material removal processes-Drilling

Material removal processes include all those where, by the nature of the process, the material is cut in order to arrive at a predetermined size. There are five basic metal-cutting processes:

  1. Drilling
  2. Turning
  3. Planing
  4. Milling
  5. Grinding

All of the other metal-removing processes are closely related to or are modifications of these five basic processes. For example, the process of boring is internal turning; reaming, tapping, and counterboring modify drilled holes and, therefore, are related to drilling; hobbing is a milling operation; honing, lapping, superfinishing, polishing, and buffing are refined grinding operations; sawing can be either milling (if it takes a circular saw) or planing (if it is done by hacksawing or bandsawing); broaching is a form of planing.

The amount of material removal of the various cutting processes may be quite small,as in polishing and buffing operations, or it may be relatively large, as in milling and turning processes. It is the purpose of this chapter to present the various material removal processes that are available to the production design engineer so that he will be able to specify the most favorable manufacturing procedure.

DRILLING


Drilling is probably the widest used machining operation. There are only a few processes, such as punching, boring, and burning, which can be substituted economically for drilling operations. All of these, however, have decided limitations; and in many cases, although another process can be used, it is still more economical to drill. Good drilling practice will result in little variation in location of holes, and size and shape can be depended upon at a minor tool cost.

The principles of cutting metal apply to drills as well as to single-point tools. The surface of the drill flutes must be smooth so that friction will not retard the movement of the chips up and out of the drilled hole. The cutting angles must be ground to suit different materials, and adequate lubrication must be provided.

The most important factor to be controlled to assure satisfactory drill performance is the accurate grinding of the drill. If one lip is ground at a different angle from the other, the tool will feed off-center and will drill an oversized hole. Also if the angles are the same, but one side is longer than the other, a thicker chip will be cut on one side, causing the drill to cut oversize. In addition, improper grinding results in an unequal distribution of forces acting on the drill, which may cause drill breakage. Drills should be ground in a drill grinder rather than by hand so that an unskilled operator can provide drills that are ground properly and save the time of the skilled operator.

Drills for different kinds of material, such as plastics, nonferrous metals, cast iron, steel, and alloy steels should be stocked in the tool crib, available for use with the particular material. The use of proper feeds, speeds, jigs, and equipment with true-running spindles will increase the life of tools, result in the drilling of more holes per hour, and give greater accuracy. Drilling is a major operation, and a small percentage saved can amount to a considerable amount of money.

Improvement in drill performance has recently been made by the introduction of better tool material, polished flutes chromium-plated to reduce wear, and improvement of the shape of the cutting edge.

DRILL TERMINOLOGY

There are 20 different types of twist drills, as well as flat drills, straight-flute drills, core drills with three or four flutes, multicut drills, step drills, multiland drills, and combination drills and reamers. In order that the possibilities of the various types of available drills might be understood, the suppliers of drills have developed data which suggest the best shape of drills for each of the large variety of materials.

DRIU EQUIPMENT

One design may require the use of several types of drilling equipment, jigs, and fixtures. A good design reduces the number of different machines and the sizes of drills, reamers, and taps used. Good designs endeavor to place the holes on a single plane and maintain constant depth of all holes drilled. Effective design and production will be made possible by a knowledge of drilling equipment, cutting tools, and auxiliary equipment.

When drilling is done, the work is brought to the fixed spindle of sensitive and upright drilling machines (both single spindle and gang drills) or the spindle of a radial machine is brought into position as the part is held stationary.

Parts are held in vises or jigs and moved under the drill spindle along the table. Often two, three, four, six, or eight spindles are mounted over one table so that the part can be drilled, reamed, tapped, or counterbored without removing the part from the jig. Quick-change chucks also enable additional drill sizes to be used on the same machine and spindles.

When radial drills are used, the part is stationary and usually in a jig. Often the jig is suspended in a trunion and can be drilled from any side parallel to the axis of the trunion. Quick-change collets enable the operator to change from one drill size to another, or from drill size to reamer, boring bar, or tap. Radial drills are designed so that feeds and speeds can be changed quickly to accommodate, use of the large variety of cutting tools.

Multiplc-spindle machines and single-spindle machines equipped with multiple-spindle drill heads may be fed simultaneously into the work. The length and time of feed are determined by the longest hole to be drilled and the drill having the lowest feed requirement. Rpm can be varied in some cases with special gearing,but rpm,s, in general, are the same for all drills mounted in the head. The drills are guided by bushings mounted on the drill press head or in the jig. Drilling, reaming,and tapping can be performed in multiple-spindle heads. Usually each operation is done in a separate machine. Wherever a number of holes can be drilled at the same time in a part of moderate activity, the multiple-spindle drill is economical. Multiple drilling is applied widely in mass production and can be economically adapted to job shop work. Bolt holes for cover plates, bearings, glands, and housings, can be standardized to use similar jigs and setups and promote the use of multiple-spindle drill presses.

DRILL TERMINOLOGY

The part, jig, and tool must be designed to withstand the pressure of the tool as it is cutting. The new cutting tool materials have raised speeds, feeds, and pressures until only the most modern equipment can take full advantage of the new features. The engineer should use the data furnished by equipment and tool suppliers as a guide, and experiment with feeds and speeds in order to remove the greatest amount of material consistent with an economical tool life. The cost of the operation and machine must be balanced against the cost of tool wear, and against sharpening and setup time.

A drill, on entering material, has a tendency to wobble until the entire drill is cutting. Thus the accuracy of the location of a drilled hole is increased by using a punch mark, a smaller diameter drill (which wobbles less), a stub or short drill rigidly held in position by a good spindle, and a guide bushing. If accurately located holes are required, it is necessary to make the part on a precision machine like a jig borer or a horizontal boring machine, or to use guide bushings mounted in a jig .

Numerically controlled turret-type drill presses with the table automatically positioned can drill, ream, tap, chamfer, and counterbore any quantity of parts without a drill jig. The table holding the work is accurately positioned, the turrets are rotated, proper speeds selected, proper advance and cutting feeds selected by a master tape or punched card. The operator merely places the tape in the control, installs the cutting tools in the turret, and locks the part on the table with vee jaws or clamps.

DESIGN CONSIDERATIONS

DESIGN CONSIDERATIONS

The most important considerations for a designer to observe are:

  1. Avoid deep holes. Any hole longer than five times its diameter is considered a deep hole and requires special procedures in the shop, such as withdrawing the tool at intervals to clear the chips, and forced lubrication.
  2. Start and finish holes on surfaces at right angles to the direction of the hole.
  3. Provide room for a bushing and its support in the jig or a fixture to guide the drill.
  4. Use standard-size drills for tapped holes and clearance holes for bolts, screws, rivets, and bushings, so that minimum stock of drills can be maintained.
  5. Use drilled holes instead of reamed holes wherever possible, provided the shop can produce good quality holes through proper grinding and tooling.
  6. Use the same size hole, or tap wherever possible, so that the minimum number of spindles and drills will be required.

Antistatic Materials

Antistatic Materials

blow molding industryTwo specific problems that may be lessened or corrected by the use of antistatic materials are found in the blow molding industry. The first deals with the presence of contaminating chips within blow-molded containers, and the second deals with unsightly dust collection on blown polyethylene parts on store shelves.

Particles of polyethylene that are forced into a container by such operations as reaming pose a rather serious problem in some container operations. Removal of the chips is costly and even the use of high pressure air does not always do the job. Due to the presence of 

static in a material such as polyethylene, these particles cling tenaciously to the blown part. The presence of these chips will cause plugging of nozzles in the bottle filling line. The smaller the filling nozzle the more serious the problem. The presence of an antistatic additive in the raw material will lessen the grip of the contaminate.

Dust collection on such plastics as polystyrene and polyethylene due to static attraction is much more pronounced than on materials that absorb moisture, such as cellulosics, and dissipate static electrical charges. Patterns are actually formed from dust that is pulled to the container or part from the surrounding air. The proper use of antistatic materials to overcome this problem is based on the incorporation of the product in the raw material. The additives are used in low concentration and therefore, must be uniformly dispersed through the plastic.

It is recommended that thorough testing be conducted on critical blow-molded parts applications before a final decision to use antistatic materials is made. The degree of exudation of the additive may alter treatment and decoration techniques of the part. The effect of the additive on stress-crack resistance must also be investigated.

The following antistatic agents are in use today: An-stac M and 2M Armid O Nopco 1009-C; Slip-EzeSequestrene NA4 “Zelec” NKGlyceryl Monosterate ENalquat G-9-12 and G-8-12. In general it is suggested that the antistats be added at the 1 part or 1 per cent level.

How to Look for in PET preform Mold Supplier

PCO28MM preform mold

How to Look for in PET preform Mold Supplier

When engineering comes to purchasing with a requirement for PET preform molds , many times the purchasing person isn’t knowledgeable enough about purchasing PET preform molds to know where to go for the requirement. In some companies, project or product engineers are in charge of finding a mold manufacturer, but even then there are questions about what to look for in a mold supplier.

Many purchasing people will go online as a first step, and there they will find a plethora of mold manufacturers. So how to pick the right one for the job? Most mold shops have similar machine tool capabilities and CAD/CAM software systems. Where the differences come into play are the mold types in which different shops specialize. Some of the types of molds include:

• Insert Molds: molds which accommodate inserts (either robotically or manually inserted) which the plastic is molded around to eliminate secondary or post-molding operations.

• Overmolding molds: molds which accommodate placement of a substrate part over which another material is molded, i.e. an ABS substrate with a thermoplastic elastomer (TPE)

• Two-shot molds: mold which are built to accommodate multi-material molding or multicolor molding, such as an automotive tail light, which might require both red and orange polycarbonate material to be molded for a complete tail light.

• Rotary Stack Molds: molds that produce multiple parts that require multiple processes. The mold is built in a “cube” and after each process the mold rotates 90 degrees for the next process. This is for highly complex components requiring both multi-material or multiple steps to complete, but the result is a final, completed and assembled unit. Eliminates secondary operations, multiple steps after molding or multiple molds to make a complete unit.

• Unscrewing molds: molds that accommodate threaded parts such as screws, caps and closures, and generally have either id or od threads.

Some  molds  manufacturers specialize in very large-sized molds such as those that would be used for bumpers on cars or trucks. Some specialize in very small molds for micro-molding. Most fall somewhere in between, and can generally handle molds that fit up to a 500-ton injection molding press. Mold manufacturers also have market niches with which they have become well-acquainted with such as extremely high-cavity molds (128 cavities for example) for the packaging industry; or smaller cavitation molds for the medical industry; or very aesthetic molds for the cosmetics packaging industry.

Mold manufacturers develop certain areas of expertise over their years in business, and generally are more successful when they stick to those areas of expertise. While it’s not impossible that a moldmaker that has only built smaller, 2, 4, 8 or 16-cavity molds could successfully build a 96-cavity medical mold, it’s best to find a mold manufacturing company that has a track record in building the type of mold that the OEM requires to help ensure everyone’s success.

For example, a mold manufacturer might be good at large multi-cavity molds, but has never built an unscrewing mold for a cap application. There are mold manufacturers that specialize in building unscrewing molds and have built hundreds over the years. The opportunity for a successful build for a large, multi cavity unscrewing mold from a shop experienced in this type of mold is much greater than one which has never built an unscrewing mold.

If the price sounds too good to be true…

You’ve heard it before – it probably is. Mold manufacturers do not have “standardized” pricing, so if you go out for bid from several different mold companies, you’ll probably get several different prices which can range all over the map. Much of this price variable has to do with the expertise of the mold manufacturer in designing and building the type of mold you require. It also has to do with their shop rates, which can vary depending on the size of the shop or where the shop is located, and other variables. But beware of a mold price that sounds just too good to be true

If you get quotes that are very wide in price, go talk to each preform molds maker that submitted the bids and ask for a detailed explanation of the quote and how he/she arrived at that price. Make sure your RFQ contained all the detailed information about the mold’s requirements and that the moldmaker didn’t miss something that might have added cost to the mold. Moldmakers are human too, and none of them are mind-readers.

Why PET preform mold need tryout before production

Why need PET preform mold tryout before production

PET preform mould

the improper design of the PET preform mold often cause the final product with some defects,especially for injection molding part for it need more precise size than blowing molding and rotational molding often. So, before the this kind of plastic mold modification, usually it need conduct a tryout or evaluation for optimization of PET preform mold design and process parameters, so as to avoid unnecessary errors, achieve good products, then meet the quality requirements of mass production.

The  steps of tryout of PET preform mold

  • Step 1. Set the barrel temperature.It should be noted that the initial temperature of the barrel must be set in accordance with the plastic material suppliers’ recommendation. This is because different manufacturers produce different brands of the plastic material which may have quite a big difference, and those material suppliers often have a very indepth study and understanding of their products.Users can have basic settings according to their recommendations, and then have the appropriate modification on the real production.In addition, it also need use the detector to measure the actual temperature of the melt. Because we tend to set the barrel temperature effected by environmental temperature, type and location of the depth of the temperature sensors,which does not guarantee 100% consistent with the real melt temperature. Sometimes, because of the presence of oil or other factors, the temperature difference between the actual temperature of the melt and the barrel is very large.
  • Step 2. Set the temperature of the PET preform mold.Similarly, the initial mold temperature settings must also refer to the recommended values from the material supplier.Note that the mold temperature here refers to the temperature of the cavity surface, rather than the displayed temperature of the mold temperature controller .In many cases, due to environmental , improper selection of the mold temperature controllers and other reasons, the temperature and the temperature of the mold cavity surface are not consistent. Therefore, before the formal tryout, cavity surface temperature must be measured and recorded. Meanwhile, the different mold cavity position should also be measured, to verify the balance temperature at various points, and record the corresponding results, provide to optimize the reference data.
  • Step 3. Based on experience, the initial plasticizing setting, injection pressure limit, injection speed, cooling time , screw speed and other parameters could be figured, and make its appropriate optimization later.
  • Step 4. Have a test to identify the switching point. Which is a stage point from the injection stage to the packing stage, it may be the screw position, the filling time and filling pressure. This is one of the most essential and basic parameters of the injection molding process . under the actual test, the following points should be followed:(1) holding pressure and holding time is usually set to zero for the first trial;(2) products filling depends on the wall thickness of products and structural design of the mold;(3) for the injection speed would effect the position of switching position, so after each change of the injection speed , we must reconfirm switching points, the material flow path in the mold cavity could be found, thereby trapped air area could be easily determined,then decide how to improve to vent the mold.
  • Step 5. Find the limit of the injection pressure. In this process, it should be noted the injection pressure and injection speed is related.For hydraulic systems, injection pressure and injection speed are interrelated. Therefore, these two parameters can not be simultaneously set best to meet the required conditions.Injection pressure on the screen is a limit of the actual injection pressure, and therefore, injection pressure limit should be set larger than the actual value of the injection pressure . If the injection pressure is set too low, the actual injection pressure is close to or exceeds the limit value of the injection pressure, which would affect the injection molding cycle time.
  • Step 6. Optimizing the injection speed. Injection speed referred to the speed which could meet the shortest filling time demand and the lowest filling pressure demand.the following points should be noted:(1) Most of the product surface defects, especially defects near the gate, are caused due to the injection speed.(2) multistage injection can not be adopted only when the one time shot couldn’t meet the needs of the process , especially in mold test stage.(3) In the good mold condition, correct switching point setting and the enough injection speed , there is no direct relationship between the injection speed and product flash.
  • Step 7. Optimization of holding time.holding time is time of the gate solidifying. In general, the holding time may be determined by weighing the products to obtain different time, and optimized holding time is when the products get its max weight.
  • Step 8. Optimizing other parameters, such as holding pressure and clamping force and so on.Finally, it should be emphasized that the purpose of PET preform mold trial is to optimize the tooling and injection processes to meet the requirements of mass production, rather than just a good test sample.


PET preform mould by stevencheng

PET preform molding technology

PET preform molding technology

In the preform molding process, the best conditions is the possible low temperature, the possible short cycle time, evenly and completely melted, the possible less IV and AA , transparent possibly. Process condition related is:

Temperature
It refers to the barrel temperature in the injection machine and the hot runner temperature of PET preform mold . On Molding process, only 30% of the heat come from the external heating, 70% is from the internal shearing heat, so in addition to the appropriate barrel coil heating, the molding also need much shear heating.

Injection and packing
Injection is to overcome the resistance of the flow , the melt is filled into a mold. On the preform molding, the best process is three stages speed and pressure setting, with descending order.
If injection speed is too slow, shearing isn’t enough, the melt would cool down before the full filling, which result in short shots; Fast filling and poor venting on the cavity would result in insufficient filling and severe shrinkage.
Packing has two important roles: to prevent backflow of melt and to ensure proper cooling under pressure (enhance the cooling effect). Too high pressure will cause excessive filling and make molds open, high internal stress and crystallizing. While too low pressure will cause shrinkage, preform deformation(poor cooling).Gate problems, such as holes, voids, and etc., because the cooling rate of decline at the gate.packing time should be appropriate, for too short packing will cause holes.

Pressure release
Pressure releasing is to reduce the pressure within the hot runner, to prevent the gate stuck and poor needle valve operation . But too much will cause shrinkage, drawing and hole.

Back pressure
Back pressure is a force applied to the melt plastic,driven by the rotation of the screw activated by hydraulic cylinder system. its function: to strengthen PET plasticizing , eliminate air bubbles. Start from 0,after preform ready then increase gradually until there is no bubble inside,at that point,it is a proper stage.Too high back pressure would lead to high shear, bad shape, gate blockage and etc.

Buffering material
Buffering material is the unfilled material in front of screw after each injection , too little will cause poor shape, while too much will cause PET to decompose. The amount is adjusted gradually from small to large, until no whiting or crystallization .

Cooling
PET raw material is opaque, while the preform is transparent , the reason is because of cooling. Poor cooling will reduce the cooling rate , lead to shrink ,preform deformation and longer cycle time.In order to avoid those situation, the following should be noted: proper water treatment, regular waterways cleaning, the water flow rate and pressure check ,core and cavity cleaning and etc.

IMAG2646

How to select hotrunner system for paint bucket mould

10 points on hot runner selection

Typically, before selecting the hot runner system  for paint bucket mould, we must  have a full understanding for the following 10 factors to select a proper hotrunner system:

  • product design. Product design is usually the first stage to be completed, and its ultimate stage is finished by the hot runner system. In order to ensure that the material in the molding process achieve better mobility, and at the end of the molding,the molded product has more smooth appearance, easy ejection, the structural design of products must include these factors;
  • plastic material. Different plastic materials have different processing characters, it generally relates to the viscosity, as well as the processing temperature sensitivity. These process variables will influence the choice of hot runner systems;
  • Product weight. Generally, for the different weight of products, their requirements for hot runner are completely different. But whether it is a small cap, or big truck bumper, it can be easily designed for their hot runner systems;
  • Cycle. Rapid production means that the high demand for the development of nozzles required, for example, the nozzle must be precisely heat transfer, and must be durable. When the temperature of the  paint bucket mould hot runner system balance is not good, it will take a big impact on the product’s shape. Generally, as to early hot runner systems, their temperature layout is often not good, but the current development of hot runner systems can provide a stable  production performance, its reliability can also meet the requirements of normal production;
  • 10L paint bucket mould. Generally, with optional hot runner system ,mold-related factors include: the number of cavities, material processing method, nozzle layout…;
  • runner. Often, people often call hot runner mold as “non-runner” plastic mold, this statement is somewhat not correct, since the so-called “non-runner” molding does not really replace the runner. In fact, the use of hot runner system aim to avoid the waste of material, thus saving raw materials, while hot runner system eliminate the runner material,previously manual and mechanical process;
  • the gate (pin point style or shut-off style). For point-gate, in order to maintain a good balance of heating in each molding cycle, the heat nozzle must have 2 funtions to melt material and cool to seal material . The shut-off gate adopts mechanical methods(moveable shut-off pins) to seal the gate;
  • the temperature control. Usually, each nozzle must be controlled by a relatively complicated temperature control unit. The PID control unit is commonly used to ensure  the heating is controlled  preciselu . Currently, this control method has been widely used;
  • Characteristic of  injection molding machine. Usually, the specific requirements of the injection molding machine includes: a given sized molds installment, sufficient clamping force, the manipulated cycle time  ,plasticize the enough material ,meet the requirements of strict temperature control and  precise injection;
  • nozzle. A variety of  kinds of nozzles, according to the general size, temperature distribution, physical characteristics, the materials  (copper, steel, etc.), maintenance and price.

How to pack jar pet prefrom mold?

How to pack jar pet prefrom mold?

Jar PET preform mold is widely used to make the pet jar preform,but how to pack this kind of mold is a problem for most of us,and the following is some tips to deal with this:

  • the preform mold cavity is coated with anti-rust oil spray.
  •  the movement components are coated with grease.
  • the sprue opening is blocked with butter
  • mold lock stripper is installed, and its specifications meets the design requirements (three plate mold  fixed to the B plate) ,at least two pieces.
  • mold drawings, structural drawings, drawing of  water line layout, spare parts and mold material suppliers details, manual, packing lists, electronic documents .
  • the surface of plastic jar prefrom mold should be painted (if any special requirements from customers, follow according to the contract and technical requirements)
  • check assembly conclusions
  • spare parts along with  the easy broken parts and the vendor name
  • film wraping
  • logo on wooden package box
  • strong wooden package box