How to Inject Silicone Molds

How to Inject Silicone Molds

·      Often castings of an object are made by injecting material into a mold. The mold may be made up of two or more pieces, which are closed before injection begins. The main benefits of this process are reduced seam lines in the product as well as allowing you to use only as much casting material as you need with little waste. When injecting material into a closed silicone mold, it is essential to take several steps to insure that the casting comes out right. If your mold was designed for this purpose with the holes already in place, begin at Step 6. 

1

Determine the best injection point in your mold. Ideally, this should be a place that is not easily seen on the cast, such as the back or bottom. Mark the point with a marker.

2

Determine the highest points in the cast. Mark these with the marker.

3

Drill a hole in the silicone at the injection point. The drill bit should be the same diameter as the tip of the syringe. Use an extremely sharp drill bit to prevent the rubber from grabbing onto the bit. It's a good idea to have a friend hold the mold in place just in case the bit grabs the silicone; otherwise the entire mold will spin and could cause injuries.

4

Drill small holes in the highest points. Use the smallest bit you have for these as they are simply to allow air to escape as you inject the casting material.

5

Mark the holes in the mold shell and drill it out as well.

6

Apply a thin coat of silicone mold release or hand soap to the entire inner mold surface with a paintbrush. Allow it to dry and buff out the excess with a paper towel.

7

Close the mold and strap or clamp it shut tightly.

8

Mix the casting material according to its instructions.

9

Pour the casting material into the syringe.

10

Insert the tip of the syringe into the injection hole and inject the casting material.

11

Allow the casting material to run out of the air release holes for a few seconds before plugging each one with a bit of clay. This allows any air bubbles in the casting material to escape the mold.

12

Once the mold is filled, remove the syringe and plug the injection hole with clay.

13

Allow the casting material to cure and dry.

14

Remove the cast from the mold.

15

Remove the knobs left by the holes with a razor blade and sandpaper if needed.

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How to Make a Silicone Mold

Silicone molds are most often used in projects that require resin or other plastic casting, and can be seen in the creation of toys, collectible figurines, props, model parts and other small plastic casting projects. Silicone rubber is usually preferred because it can be used with many materials and it does not stick to itself or other objects, negating the need for a mold release agent or a separating wall during the molding process. The most common type of silicone mold is the two-part mold, which creates a seamless end product.

Instructions

1

Build a molding box for the model object you would like to make copies from. For smaller objects, make your box walls from Legos, and roll out a flat piece of modeling clay for the bottom of the box. For larger objects, build the box walls and bottom from sturdy cardboard or wood. Make sure that the box gives your model a clearance of at least 1/4 inch on all sides.

2

Mix together half a batch of silicone RTV rubber and catalyst, following the packaging directions for the brand of rubber you have. Make sure that the catalyst is completely blended into the rubber, creating a pale version of the catalyst's color.

3

Mark the halfway point on your molding box with a pencil or marker. Pour the batch of silicone rubber into the molding box, and stop at this halfway mark.

4

Press the model object into the siliconerubber until it is half covered and does not touch the sides of the molding box. Let this half of the mold cure, or dry, overnight or for 12 hours.

5

Mix together the rest of the silicone RTV rubber, and pour it into the molding box, covering the model object completely. Let the rubber cure overnight.

6

Take the molding box apart and separate the mold halves, removing the model object. Fit the mold halves back together and secure them with rubber bands.

7

Carve a pouring hole in the top of the mold at the joining line with a razor blade or utility knife. Cut the hole deep enough to penetrate through the rubber and reach the inside cavity.

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How to Find Quafiyied Plastic Injection Molding Companies

How to Find Qualified Plastic Injection Molding Companies

Selecting the best plastic injection molding company from the suppliers out there can be a difficult task. Let's take a look at how to find the best molding company for you budget by following these steps.

Instructions

1

First, in order to begin evaluating plastic injection molding companies, it is important to know what you need them to mold for you. Specifically, you will need to have a fully defined 3D Model and engineering drawing of the plastic component you wish to have molded. Be sure to fully specify draft angles and surface textures in drawing.

It is important to also specify things like maximum allowable flash.

2

Next, it is critical to realize that for most companies seeking an injection molding supplier, for right or wrong, the largest factor tends to be cost. Going oversees to places like China or Korea usually results in a lower piece cost than staying in the United States. However, this savings in cost per molded part can be offset by delays in getting the product to market.

Based on the project your company is working on, determine if there are absolute restrictions on price as this will be important to know.

3

Next, when evaluating a potential injection molding company, it is very important to learn about the history of the company and their capabilities. How long have they been in business and what industries do they typically mold parts for?

If you have a part that requires extremely tight tolerances, an injection molding company in the health or aeronautics industry may work out better than a company that molds toys.

4

After you learn about the background of the company, investigate their capabilities. What type of molding capabilities do they have? Do they have any specialties such as 2-shot molding or insert molding?

What type of presses do they use and how old are they? Are they able to handle the volumes or quantities that you require?

As alluded to earlier, lower molded component cost does not always translate to an overall savings. Depending on the quality control of the molder, their quality may be sub par resulting in delays in the schedule or worse...returned product from the customer.

Take some time to understand how the plastic injection molding company monitors and ensures quality. Do they do control charting? Are they ISO certified? Ask to see examples of quality records/documentation for some of their recent projects.

If some unacceptable product is found during an audit, what is their corrective action plan? Do they quarantine the last X hours of product?

5

Lastly, the location of the supplier can also be very important. Where are they located and how will this impact your working relationship? Having an injection molding supplier "right in your backyard" so to speak is great as it allows you to make day trips to the supplier when issues arise. Contrast this to going overseas to an Asian supplier where it will cost thousands of dollars per person per trip to visit.

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Silicone Mold Problems

 

Frequent Questions

1 . Why silicone mold appear less turning model ?

In the process of making molds adding too much silicone oil, silicone oil destroys the molecular weight silicone , so the mold will be fewer non-durable turning model such phenomena . If molding more complex patterns products come with a large hardness silicone mold , there will be fewer turning model of the phenomenon , because silicone excellent time will be very brittle , easily broken . Conversely , if you do build a product to do with a small hardness silicone mold , the result would be equally unsatisfactory . Because the silicone is too soft, it will reduce the tensile and tear strength , made ​​out of the mold will be deformed , so turning model number will be reduced. Plastic mold itself is very good quality , silicone no good or bad , only suitable or unsuitable . We should adopt appropriate size product hardness silicone to make a mold.

2  Why silicone mold have burning phenomenon ?

Because unsaturated resin and resin product added peroxide curing agent after the reaction in case of resin will produce a lot of heat, general resin curing time of 3 minutes, three minutes after going to release soon , will prevent the silicone mold burning problem

3 Why silicone mold will appear in the table dry quit phenomenon ?

Silicone mold belongs condensation silicone , which is absorbed by the moisture in the air and cured silicone in the process of making , the water evaporated , while there is no transferred amount of water, this phenomenon occurs . Solution: This phenomenon does not belong to product quality issues , but because there is no control of moisture , silica gel to enhance shelf life , shelf life of these phenomena appear long , long time using silica gel , add amount of 0.05% water ,  the problem can be solved.

4 Why silicone mold appear poor tension phenomenon ?

Because the client in the production process of the mold in order to reduce the viscosity of silicone , silicone easy to make large amounts of silica in a silicone oil is added , this will become very soft silicone that produce intolerance pulling the tear strength is reduced , Rally deterioration phenomenon resulting mold is not durable , life is short, less turning and so on.

5 Why mold will appear oil flush?

Silicone mold itself have no oil flush problem , just because during operation adds composite silicone ( silicone oil with white mineral oil complex ligand ) as white mineral oils are petrochemical products, not silicone .

6 Why mold have aging phenomenon ?

In the process of making silicone molds , we recommend our customers the best without any oil, if necessary , the amount of silicone oil added up to no more than 5 % to 10 %. Because the addition of silicone oil will destroy the molecular weight silicone too , so do not come out of the mold will produce acid , intolerant aging phenomenon.

7. Why silicone mold have surface marks , stripes, not smooth and so on ?

This phenomenon is a product or a model to be replicated no grinding or polishing sake. Because in fact the model or the product itself is not enough to smooth or perfect , so the product or model to be copied if not polished or polished , even the best silicone molds will do pretty, is not smooth enough . Another case is , when playing a release agent , no uniform brushing can also cause mold surface problem.

8  you know the usage of mold silicone?

Silicone mold is mainly used for toy and gift industry , craft industry , furniture decoration industry , figures copied , building decoration industry , resin handicraft industry , unsaturated resin crafts industry , candle craft, Plastic toy industry ,Gifts stationery industry,Gypsum gifts industry, mold manufacturing industry, Bolero industrial , simulation plant and animal sculptures, Buddhist carvings crafts products and other industries copy and mold making .

Mainly in used in toys , gifts, floral fine products for packet mode , filling mold products , glass , lighting , candles , figures copy production molds , large products , open- slice mode , relief , statues , gifts making molds , sole model , perfusion mold, sand- casting.

A variety of different uses specific operations silicone mold is also not the same , what is required to achieve the specific operation must be based on a variety of different parameters.

 How to clean

General production mold clean up our way is the use of sandblasting ,place the silicone products mold into blasting machine, blasting head is aligned with the production of silicone products mold cavity , and then gradually Sort cavity by sandblasting .

 

 

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what's silicone molding?silicone mold, mold silicone

Silicone Mold

Silicone molds are produced crafts special mold rubber, silicone is characterized by high temperature, corrosion resistance, tear resistance and strong , high simulation fine , special molds for making all kinds of crafts .

 

Silicone mold materials

Silicone is good for its environmental performance and more and more people know and understand the silicone mold , let’s start form silicone raw materials .

1 , according to the performance of raw materials, silicone can be divided into ordinary silicone and The pure silica gel

Ordinary silica also known as precipitated silica ,

Color: translucent, milky white , pale yellow , gray and so on.

Hardness : 30 °, 40 °, 50 °, 60 °, 70 ° , commonly between 40 ° -70 °.

Density :1.1-1 .12g/cm ³

Elongation: 400%

Uses: more used on phone keypad, miscellaneous items, such as middle and low conductive silicone rubber products .

pure silicone rubber Color: Clear .

Hardness : 30 °, 40 °, 50 °, 60 °, 70 °, 80 ° , commonly between 40 ° -60 °.

Density :1.1-1 .12 g / c ㎡

Elongation: 600% -700 %

Features : Because this material is good transparency , strong tensile . High cost

Usage: silicone tube, protective cover and other high need high flexibility products .

2 , according to the physical properties of silicone raw materials, can be divided into solid silicone and liquid silicone .

Solid silicone is mainly used for molded products. For example: silicone case , silicone utensils , silicone molds, silicone keys , etc., mainly used for liquid silicone extrusion products, such as silicone nipple , silicone tubes.

Insulation silicone pad , excellent heat capacity , silicone ( food-grade silicone ) resistant to 200 ℃ high temperature and long-term use , the production of raw materials meet food grade standards , through FDA food-grade test , tasteless , non-toxic , mold manufacturers in accordance with production, color, shape can be customized .

 production process

Molding form and mold parting line is very important.  first, to take the easy mode , the second is the parting line should be selected without affecting the overall effect of the product, the third is not to affect product quality , such as mold line position waterscape series too high , sealing materials and more time to mold line of products prone to cracking ; fourth step is to reduce the flow of operations , such as opening half of the mold .

In order to prevent the flow around the silicone mold, use some slice for blocking the certain area , no gap , oil smooth surface . After completion of the above work to prepare , and then on the kinds of painted plaster mold or mold release agent on Vaseline or spray , smooth product requirements with a clean cotton cloth soaked in Vaseline evenly on the mold, the mold for 30 minutes species to fully absorb Vaseline , and then a clean cotton cloth to clean the surface of the mold require bright surface ; rather have the texture of the product as long as evenly coated with Vaseline on it will be better formulated silicone tune. When the direction of the irregular silica gel formulation should be agitated to mix the curing agent and silicone sufficiently minimize pumping to maintain a vacuum of the required air -0.1Mpa within the mixed rubber , smooth product is best when the adhesive coated first layer 7-8 seconds.

With a good silicone molding should be timely . The glue in a way trickle down to the highest parts of the mold , let it flow , where the flow is not in place with a painting brush in place, if it is not only full piece molded silicone brush evenly throughout the product but also on clay . Each item of each brush at least three silica layer thickness of silica 1mm, the brush process silica required to brush after each additional layer of the cured layer , the third layer when the brush is applied to the top of a second layer layers of gauze to increase the strength of the silica gel . Entire mold silicone products based in part on the size of the different requirements of thickness control in 3-4mm, width no greater than the product width 60 mm. Start silica gel solidification time was 20 minutes.

1 , clean and dry the female die, (brushing a layer of mold release wax release agent )

 2, 500-1000 grams of silicon rubber mold ( silicone molds , rubber molds , silicone rubber , silicone ) keep well for spare ;

3 , weight certain proportion hardener ( typically 1.5-2.5 % ), put in a container, mix and stir ;

4 , depending on the situation (especially for the first layer ) by adding a certain amount of silicone  dilution. Until thoroughly mixed up , usually 3-5 minutes.

5. Silicon rubber mold ( mold silicone mold , silicone rubber , silicone ) and the curing agent mixture , i.e. the reaction at room temperature , and the release of low molecular weight alcohol , the alcohol molecules from the colloid is required under the negative pressure discharge bulbs 1-3 minutes. Also available ( depending on the tool maker’s experience ) without the aid of equipment.

6 , multi- piece mold brushing should follow inner, middle and outer while curing appropriate. Curing agent is relatively low, the reaction time is lengthened , the reaction fully , like colloids , thus curing agent is preferably within a little more than outside . When brushing until the first layer ( inner layer ) dry and then brush a second layer . Operating time 30-50 minutes , removal time 10-15 hours. Curing time 24 hours . Note brushing first , the best use mold cloth , which can greatly improve die life ( but must not use the glass fiber cloth , or likely to cause mold scrap )

7 , three-dimensional perfusion mode , generally 10-15 hours curing as well.

8 , but also of the soft mold produced coat plaster or fiberglass to support soft silicone mold Note : 1 , analog line options: Choose the location does not affect the appearance of the product ; selection position after filling easy processing ; choose mold itself is easy to dismantle location mold ; select products easily deformed position 2 , the production schedule must not rush blindly to increase the amount of hardener , otherwise it will greatly reduce the silicone mold life.