Adhesive bonding is one of the most common joining technology available. you can easily purchase a cyanoarylate (commonly known as super glue) from a stationery shop to glue your broken mug with a couple of dollars. It is easy to used, and it serves well in most condition. There are still many types of adhesive if this isn't suitable for you, such as epoxy, anaerobic, etc...
Lets first have a look at epoxy, which usually consists of epoxy resin + hardener. It is easy to use, simply mix the resin with the hardener together so that the end parts of the adhesive (diepoxy and diaming) are joined, and apply them on adherents. It wouldn't take long to polymerise, so you have to act fast before they cure, or simply make everything ready before you mix them togethher. However you may find that it is very hard to remove the adhesive from the substrates once it cured, so always act wisely and carefully.
The next one, anaerobic, which means 'no oxygen or lack of oxygen'. So the polymerisation basically happens when there is little or no oxygen at the surrounding. Apply the adhesive on the adherent, but the adhesive will remain as it is when there is oxygen around. But once there is a lack of oxygen, the process initiates and it happens just within a flash of seconds. So this process is usually used for thin closed gaps.
Super glue is a type of adhesive which cure very fast as well. The water vapours in the surround atmosphere act as initiator to begin the process. It is suitable for wide range of material, but it is flammable under high temperature so you can see the burning cautions at the rear of a superglue tube. One common point for these adhesives is that they formed thermoset instead of thermoplastic in the curing process.
Sunday 26 May 2013
Saturday 11 May 2013
Adhesive bonding
Adhesive bonding is another option if you would like to join 2 or more parts together. It is similar as glue-ing parts together without the need of high temperature involved in the process. This joining process fit in many applications in the industry because it can bond almost all materials.
There are many types of adhesive bonding available in the shop out there. We will talk about some of the common types available. Super glue is one of them and it can be purchased in most stationery shops. The technical name for super glue is cyanoacrylates. It has low viscosity and generally not cheap if you consider its volume. When super glue is exposed to the air, it undergoes rapid polymerisation reaction. The moisture in the atmosphere acts as initiator and the process can finish in just a few seconds.
Another common adhesive is epoxy which consists of both epoxy resin and hardener. They are usually sold together as a set. Epoxy can be used in a wide variety of different materials such as metals and polymers. At low temperature, epoxy is very brittle but at high temperature, it becomes stronger and more durable.
Always bear in mind that before applying adhesive on the materials, some preparations are required. Basically you have to make sure the adherent surface is clean and ready to hold the adhesive. This is important to make sure a strong bonding is formed between the adherent and adhesive interface. For example, a metal piece usually tends to have an oxide layer on its surface. If this oxide layer is not 'wipe out', the adhesive will stick on this oxide layer instead of the adherent real surface. Sometimes other contaminants might occur as well, so make sure you remove them beforehand. In case the surface is rough and unbalanced, a file can be quite handy in smoothening the surface. A smooth surface is more desirable in adhesive bonding because the adhesive can spread more evenly and cover a larger surface area. Don't look down at these small tips, they are very useful if you want to make sure the adhesive really does its' work.
There are many types of adhesive bonding available in the shop out there. We will talk about some of the common types available. Super glue is one of them and it can be purchased in most stationery shops. The technical name for super glue is cyanoacrylates. It has low viscosity and generally not cheap if you consider its volume. When super glue is exposed to the air, it undergoes rapid polymerisation reaction. The moisture in the atmosphere acts as initiator and the process can finish in just a few seconds.
Another common adhesive is epoxy which consists of both epoxy resin and hardener. They are usually sold together as a set. Epoxy can be used in a wide variety of different materials such as metals and polymers. At low temperature, epoxy is very brittle but at high temperature, it becomes stronger and more durable.
Always bear in mind that before applying adhesive on the materials, some preparations are required. Basically you have to make sure the adherent surface is clean and ready to hold the adhesive. This is important to make sure a strong bonding is formed between the adherent and adhesive interface. For example, a metal piece usually tends to have an oxide layer on its surface. If this oxide layer is not 'wipe out', the adhesive will stick on this oxide layer instead of the adherent real surface. Sometimes other contaminants might occur as well, so make sure you remove them beforehand. In case the surface is rough and unbalanced, a file can be quite handy in smoothening the surface. A smooth surface is more desirable in adhesive bonding because the adhesive can spread more evenly and cover a larger surface area. Don't look down at these small tips, they are very useful if you want to make sure the adhesive really does its' work.
Friday 10 May 2013
Mechanical welding
Mechanical welding is very desirable for a few reasons. But first of all let me explain what is mechanical welding. It refers to the joining process in which forces are created between interlocking surfaces to hold the components together. There is no heating required unlike fusion welding and solid state fusion. Besides it is a cheap joining process because no additional heating and shielding etc are needed like in arc welding. What you might need includes the fasteners and tools. Besides, the process is simple and no extensive training or experience is required prior to working. A great example is that users all around the world can easily unscrew the screws in their cpu casing.
Basically there are 2 types of mechanical welding, namely mechanical fastener and integral mechanical attachment. The former refers to an additional device which is used to faster up the object, while the latter is usually a pre-designed structure which hold the object using mechanical principle. A good example for mechanical fastener is a bolt and nut combination. While for integral mechanical attachment, you can think off the snap fit design in your mobile phone, either the casing or the battery cover in which no additional device is required. This improve its beauty and make it very user friendly. However care must be taken when dealing with it because inappropriate stress or load might break it off. Also frequent dis-assembly might loosen the structure due to high friction. In case you are using an additional device to hold your object, you have to pre-drill a hole to fit the device. Drilling also incur stress concentration at the surrounding and residual stress might build up around the hole and thus affect the mechanical structures and properties. Also when the item is heavily used (e.g. in a rocking chair) the nut might drop off and poses danger to the user as well. You usually will need additional tool to assemble or disassemble the device, unlike integral mechanical attachment you can do it without additional tooling. But this mechanical fastener usually could create a higher clamping force and sustain higher loads. So there are pros and cons like a two-edged knife, you have to choose the most appropriate welding mechanism for the application. You might need to calculate the relative stress the device can hold, and the lowest stress is usually the one that causes failure in the joints.
Basically there are 2 types of mechanical welding, namely mechanical fastener and integral mechanical attachment. The former refers to an additional device which is used to faster up the object, while the latter is usually a pre-designed structure which hold the object using mechanical principle. A good example for mechanical fastener is a bolt and nut combination. While for integral mechanical attachment, you can think off the snap fit design in your mobile phone, either the casing or the battery cover in which no additional device is required. This improve its beauty and make it very user friendly. However care must be taken when dealing with it because inappropriate stress or load might break it off. Also frequent dis-assembly might loosen the structure due to high friction. In case you are using an additional device to hold your object, you have to pre-drill a hole to fit the device. Drilling also incur stress concentration at the surrounding and residual stress might build up around the hole and thus affect the mechanical structures and properties. Also when the item is heavily used (e.g. in a rocking chair) the nut might drop off and poses danger to the user as well. You usually will need additional tool to assemble or disassemble the device, unlike integral mechanical attachment you can do it without additional tooling. But this mechanical fastener usually could create a higher clamping force and sustain higher loads. So there are pros and cons like a two-edged knife, you have to choose the most appropriate welding mechanism for the application. You might need to calculate the relative stress the device can hold, and the lowest stress is usually the one that causes failure in the joints.
Thursday 9 May 2013
Why Joining?
Joining is a process to fasten or join two or more components to form a single material.
One might ask what is the reason for joining them together? Well, basically there are few reasons for doing so. First, joining enables the material to preform the desired function (e.g. to improve its thermal conductivity). Second reason is to join small parts together to form a large model because manufacturing a large object might be very expensive (e.g. moulding or casting a large piece might cost a few thousands). Hence, joining is a cheaper alternative in the industry. Lastly, it can improve the beauty of the product.
However it doesn't mean that there is no drawback for this process. Joining might alter the mechanical properties of the parts being fastened together (e.g. heat affected zone might reduce the strength of material). If mechanical joining is used, it might induce stress concentration around the pre-drilled hole. Joining is considered as an additional step in manufacturing process, which means it add cost to the production. As we know, joining rarely occurs at the beginning of the process but instead at the end phase. A failure in the joining process will ruin the production and incur higher loss to the company because it can be rarely fix. Joining assembly such as bolt and nut can be accidentally removed or dropped off during its service life.
There are different types of joining technology available such as welding, mechanical joining and adhesive bonding. Welding includes fusion welding, non-fusion welding and solid state welding. Fusion welding is the process where the materials are being heated and melted to form a single piece. Non-fusion welding includes soldering and brazing. In non-fusion welding, the materials are heated but not melted. Instead, the filler material is melted to fill the gap and form the bonds. Solid state welding happens at low temperature (not reaching the melting point of the material) but high pressure. There is no filler metal being used in the latter.
One might ask what is the reason for joining them together? Well, basically there are few reasons for doing so. First, joining enables the material to preform the desired function (e.g. to improve its thermal conductivity). Second reason is to join small parts together to form a large model because manufacturing a large object might be very expensive (e.g. moulding or casting a large piece might cost a few thousands). Hence, joining is a cheaper alternative in the industry. Lastly, it can improve the beauty of the product.
However it doesn't mean that there is no drawback for this process. Joining might alter the mechanical properties of the parts being fastened together (e.g. heat affected zone might reduce the strength of material). If mechanical joining is used, it might induce stress concentration around the pre-drilled hole. Joining is considered as an additional step in manufacturing process, which means it add cost to the production. As we know, joining rarely occurs at the beginning of the process but instead at the end phase. A failure in the joining process will ruin the production and incur higher loss to the company because it can be rarely fix. Joining assembly such as bolt and nut can be accidentally removed or dropped off during its service life.
There are different types of joining technology available such as welding, mechanical joining and adhesive bonding. Welding includes fusion welding, non-fusion welding and solid state welding. Fusion welding is the process where the materials are being heated and melted to form a single piece. Non-fusion welding includes soldering and brazing. In non-fusion welding, the materials are heated but not melted. Instead, the filler material is melted to fill the gap and form the bonds. Solid state welding happens at low temperature (not reaching the melting point of the material) but high pressure. There is no filler metal being used in the latter.
Wednesday 8 May 2013
RP (Rapid Prototyping) vs AM (Additive Manufacturing)
Rapid Prototyping & Additive Manufacturing, are they the same?
In short, no is the answer. Well I guess you wouldn't want to stop here, lets have a look on the differences between them.
RP (Rapid Prototyping) has been discussed in the earlier post, in case you need to have a quick refresh, click here
AM (Additive Manufacturing) is also known as 3D printing, it means producing end parts by converting computer data into solid 3-dimensional objects. Well it also goes layer by layer hence the name is called.
The size of AM machine is usually smaller compared to a RP machine. This means the end products are usually small in size for AM machine. But it is more versatile and can comfortably fit in an office environment or home desk without consuming huge space. Also, the price of an AM machine is relatively cheap and usually ranges from few hundreds to thousands dollars whereas a RP machine might cost you a couple of thousands dollars. From the huge price difference, one should expect to obtain a lower accuracy end product from AM. Also, the material availability for AM is quite limited, however massive R&D is being carried on, and it is believe that more variety of materials or even mix materials can be used in a single manufacturing process.
In short, no is the answer. Well I guess you wouldn't want to stop here, lets have a look on the differences between them.
RP (Rapid Prototyping) has been discussed in the earlier post, in case you need to have a quick refresh, click here
AM (Additive Manufacturing) is also known as 3D printing, it means producing end parts by converting computer data into solid 3-dimensional objects. Well it also goes layer by layer hence the name is called.
The size of AM machine is usually smaller compared to a RP machine. This means the end products are usually small in size for AM machine. But it is more versatile and can comfortably fit in an office environment or home desk without consuming huge space. Also, the price of an AM machine is relatively cheap and usually ranges from few hundreds to thousands dollars whereas a RP machine might cost you a couple of thousands dollars. From the huge price difference, one should expect to obtain a lower accuracy end product from AM. Also, the material availability for AM is quite limited, however massive R&D is being carried on, and it is believe that more variety of materials or even mix materials can be used in a single manufacturing process.
Thursday 2 May 2013
Rapid Prototyping (RP)
What is Rapid Prototyping (RP)? What are the advantages?
From the name itself, RP means producing prototypes rapidly
Compared to traditional prototyping manufacturing process, the main objective of RP is to reduce the cost and time. Cost is the most critical element you would think of when you are running a business, a lower cost indicates a higher net profit or more affordable by customers. The time here is closely related to lead time, which is the duration from sourcing raw material to customer acceptance.
Besides, RP is able to produce parts with higher complexity consistently without being fatigue like a human. Conventional prototyping are man made, and often high skills are required to produce accurate and complex components. We all know that to get up to that level, practices and experiences are a must. A person might be spending years to reach that level, but nowadays with RP, even a novice could produce a high quality prototype using RP processes. Also RP is able to produce complex models such as nested ball etc
Currently there are a number of RP systems available in the market, most commonly used is the SLA. SLA uses laser beam to solidify the polymer which turn into solid. The laser traces each layer and the blade re-coats the surface once a layer is cured. This process is repeated for a few hundred or thousands time depends on the model geometry and complexity.
From the process above, we found that RP process actually build the model layer by layer. This is something very different from old technology like moulding, or even longer history subtractive method. RP offers a good technique to form a part from software drawing to solid object within few hours instead of days or weeks. It is an emerging technology and it has drawn a lot of attention from entrepreneurs and medias. The reason for the former to be eyeing on this technology is because people know that technology is changing business nowadays, and they are determined to find out how RP will change their businesses in the short and long term visions.
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