Today we will talk about seams that are made on a sewing machine. Machine seams are divided into 3 main groups - connecting, finishing and edge. By studying the types of seams, understanding how each seam is made and practicing on samples, you will ensure that all seams in your products are made perfectly.
Connecting seams
Stitched seams are used to stitch together parts of a product, and are the most common when sewing products. Stitched seams are made using a simple machine stitch. The stitch length depends on the fabric and the purpose of the seam.
Rice. 1. Types of seams - connecting
Stitch seam "on edge"
To form a stitch seam, place two parts on the edge with their right sides inward, align the cuts and machine stitch at a distance of 0.5–2.0 cm from the edge.
The seam can be made either without a fit or with a fit of one of the parts being sewn. When making a seam
with the fit, the upper part is seated. The rib stitch is used when connecting sleeves to armholes, pocket burlap parts, and also when making other stitched seams.
Pressed stitch seam
When making a stitch seam, ironing is first done stitched seam on the edge, then the allowances are ironed and both allowances are ironed on one side. The pressed seam is used to connect side, shoulder and other seams of products made of thin fabrics.
Pressed seam
When making an open-iron stitch seam, first make a stitch seam on the edge, then iron the stitching, iron the seam allowances to different sides. The seam is used to connect side, shoulder and other seams of products.
Rice. 2. Types of seams - connecting patches
Overlay seam with open edges
To make an overlay seam with two open cuts, the parts are placed on top of each other with their right sides up and stitched at the same distance from the cuts. The cuts are left open. The width of the allowance is 0.2–0.7 cm. This type of seam is used when sewing fabric items that do not require processing - loden, sheepskin fabrics, parts of gaskets, etc.
Overlay seam with one closed cut
When making an overlay seam with one open cut, first make a stitch seam on the edge. Then the stitching is ironed, the seam allowances are pressed onto one of the parts, along which a finishing stitch is laid on the front side. The distance from the stitching line to the sewing line depends on the model, 0.5–1.0 cm.
If the model provides two finishing lines, then the distance from the stitching line to the first stitching line is 0.2 cm. The distance from the first line to the second is 0.5–0.7 cm.
An overlay seam with one open cut is used to connect parts (for example, a yoke with a front) in the manufacture of clothing.
Overlay seam with two closed cuts
a) To make an overlay seam with two closed cuts, the edges of the cuts are folded to the wrong side or basted by 0.5–0.7 cm. One edge is placed on the other and a stitch is laid at a distance of 0.1–0.2 cm from the folded edges This seam is used to sew belts, straps, cuffs, etc.
b) The second way to make an overlay seam with two closed cuts is to bend both cuts by 0.5–0.7 cm, apply it to the product and stitch at a distance of 0.2 mm from each edge. Used when making drawstrings.
Rice. 3. Types of seams - connecting seams
French seam
To make a French or double seam, the parts are folded inside out and stitched with a seam width of 0.3–0.5 cm. Then the part is turned right side out and the stitching seam is straightened so that it is located along the edge. The second line is laid at a distance of 0.5–0.7 cm from the fold so that the cut of the seam is sealed inside. This type of seam is used when sewing clothes from loose and transparent fabrics.
Covering seam
To make a sewing seam, two parts are folded with their right sides inward, the allowance for one part is cut to 0.5 cm. Then the parts are ground down. The allowances are folded to the side of the part so as to cover the smaller cut. The cut of the larger allowance is folded and a second line is laid at a distance of 0.1–0.2 cm from the folded edge. The width of the sewing seam is 0.7–1.0 cm. The sewing seam is used for making bed linen, as well as in products made from thin fabrics without lining, denim clothing.
Lock seam
The lock seam is similar in design to the closed seam, but is performed a little differently. First, an overhead suture is made with two open cuts. Then each part is turned back into a cut
and adjust according to the allowance. The lock seam is very durable and is used when sewing products that require reinforced stitching - work clothes, backpacks, etc.
Rice. 4. Types of seams - finishing
Topstitch stitch
To make a topstitch seam, first a stitch seam is made, then the seam allowances are laid out in different directions and two finishing lines are laid on the front side at the same distance from the stitch line. The distance from the stitching line to the unstitching line depends on the model (0.2-0.5 cm), from the seam cut to the unstitching line - 0.2-0.5 cm. The unstitching seam is used for joining sections of products made from materials where the seams are ironed not allowed. For example, in leather goods.
Backstitch
To make a seam, you need to mark the required width of the fold, lay the fold according to the marking and stitch it. The seam is used to make folds on products.
Open cut adjustment stitch
To make an open-cut adjustment seam, you need to stitch the part according to the markings, turn it right side out and topstitch along the edge. The seam allowance remains open. This seam is used when making pockets, yokes, etc.
Closed bevel adjustment stitch
It is performed in the same way as an open-cut adjustment stitch, but the seam allowance is cut off and stitched inside with a finishing stitch. This seam is used when making pockets, yokes, etc.
Rice. 5. Types of seams - finishing
Overlay seam with edging
Place the edging between the parts according to the markings and stitch. Place the stitch at a distance of 0.3–0.4 cm from the edge of the edging. Turn the parts right side out, place allowances on one of the parts, and iron. It is used for finishing seams on the front side of products and on the lining.
Overlock seam with edging
Fold the edging with the piece of the product and stitch. Turn the parts right side out and iron them. This type of seam is used when finishing pockets, collars, bed linen, etc.
Rice. 6. Types of seams - edge
Open cut edge stitch
When making a seam, the bias tape is attached to the product part at a distance of 0.5 cm from the edge, folded over to the front side and adjusted 1 mm to the right of the edge of the tape. The inner cut remains open and can be covered with a lining or left open, depending on the product.
Closed-cut edge stitch
When making a seam, attach the bias tape to the seam allowance of the product at a distance of 0.5 cm from the edge, wrap the seam allowance with the tape, tuck the edge of the tape and stitch at a distance of 0.2 mm from the edge. It is used when edging sections of products without lining.
Edging with braid
When performing edging with braid, braid with closed cuts is used. The width of the braid is determined by the model. To make a seam, the edge of the part is wrapped with braid, folded in half, and a seam is laid along the edge of the braid. Used for edging pockets, collars and other parts.
Framed edge stitch
To make a seam, the bias facing must be folded in half and ironed. Apply the facing according to the markings, sew a seam, bend the facing, and iron it. This type of seam is used when processing pockets into a frame.
Overlock seam "In split"
When making a split seam, first make a seam “on the edge”, then turn the parts to the front side, straighten the seam so that it is located along the edge. The seam is used when processing belts and other double-sided parts.
Overcast seam "in edge"
When making a split seam, first a seam is made “on the edge”, then the parts are turned to the front side, the seam is straightened to form an edge on one side. The seam is used when processing hems, collars, cuffs and other parts of clothing.
Rice. 7. Types of seams - edge
Overlock seam with closed binding
To make a seam, you need to bend the binding in half, stitch it to the part of the product along the edge at a distance of 0.5 cm from the edge, turn the binding to the front side and stitch along the edge. This seam can be used to process the bottom of parts and sleeves, lining pockets, etc.
Overlock seam with double tape
To process a seam, you need to stitch one side of the binding along the edge of the part, turn the binding to the front side, fold it along the edge and stitch at a distance of 0.2 mm from the edge of the binding.
Rice. 8. Narrow edge seams
Moscow seam
To complete the seam allowance, you need to turn it up 0.5 cm and sew a stitch at a distance of 0.2 mm from the edge. Cut off the excess allowance, bend the edge of the part by 0.3 mm and lay a second line on top of the first. The Moscow seam is used for finishing the edges of items made of thin fabrics - scarves, shawls, etc.
Zigzag
To make a zig-zag seam, you need to fold the cut and stitch along the edge. The stitch width and frequency are determined by the model. Trim off excess allowance. This seam is used for processing the edges of flounces, sewing knitwear, etc.
Hem seam with open cut
A hem seam with an open cut is made in this way: the seam cut is treated with an overlock stitch, the seam allowance is folded and adjusted.
This seam is used when hemming the bottom and sleeves of products.
Closed hem seam
When making a hem seam with a closed cut, the seam cut is folded by 0.5–0.7 cm. The stitch is laid at a distance of 0.2 cm from the edge.
Hand stitches and seams are most often used for needlework and embroidery. But often, you can’t do without them when sewing clothes on a sewing machine. Every seamstress must be able to perform hand stitches and various types of hand stitching, since you cannot do without an ordinary hand needle and thread when basting clothing parts and carrying out fittings.
Hand stitches will be required when connecting cushioning materials to the main fabric of the product. The skins are joined using a furrier's hand stitch. natural fur, for example, when sewing fur mittens or a fur vest.
There are many types of special stitches used in embroidery. But, we suggest that you familiarize yourself only with the basic types and types of hand stitches and stitches used in sewing clothes.
Any clothing is washed off before trying on. A running hand stitch should connect the cut details well and at the same time unravel easily. These are the properties that hand stitches for basting cut details have. This is the most common hand stitch, used by tailors.
Hand basting stitches are also used to mark the sewing line for darts, laying folds and applying relief lines to the fabric.
It is advisable to use a contrasting thread color for running stitch.
2. Hand bias stitch, goat stitch
Blind hand stitches are used to hem open-cut items of non-flowing fabrics. These stitches are sewn over the edge. The thread should not be tightened too much. This stitch can be used to create an invisible hem on a skirt, dress, etc.
The cross stitch is made from left to right, forming a cross stitch.
Hand cross stitch has many varieties and is often used for decorative purposes and hand embroidery.
3. Technique for performing a blind hem stitch
To make a blind stitch, the fabric at the edge of the folded edge needs to be slightly folded. After this, pierce the fabric with a needle to the desired depth (depending on the thickness of the fabric). Without moving the needle to the other side, make a through puncture on the folded edge of the fabric. The thread in the stitches does not need to be tightened, just slightly pull up the excess thread. It is recommended to sew a blind hem stitch from left to right.
The lining is connected to the product using hidden stitches and the folded edges are hemmed.
4. Overlock, hand stitch
If your sewing machine does not produce buttonholes, then buttonholes on clothing can be made by hand using buttonhole stitches. Loop stitches are used to overcast the edges of a cut loop, and also to process the edges of non-flowing fabrics, instead of using an overlocker.
Most often, the overlock stitch is used as a type of hand stitch used to overcast the cut of a buttonhole. The fabric should be pierced 2-3 mm from the cut line and a loop should be made by throwing the thread behind the needle. This seam can be used decorative finishing leather souvenirs, homemade rugs, etc.
5. Hand stitches "back needle"
A hand stitch consisting of such stitches is considered the most durable among all types of hand stitches. It is advisable to use it when you need to restore a machine seam in hard to reach places. It is convenient to use when you need to attach facings to seam allowances in items made from thin fabrics. This seam can be used to manually sew on a zipper, etc.
A hand stitch with a back needle is done from right to left. Make a small stitch, insert the needle into the fabric, to the right of the point where the thread comes out of the fabric.
6. Types of stitches. Hand stitch "flock"
This is a professional tailor's stitch used in sewing outerwear, fur hats. This hand stitch is used by tailors for discreet sewing and securing parts of outerwear, such as hems men's jacket, coat. Also used in the manufacture fur collars. The needle on the front side captures a barely noticeable area of fabric, and with inside The needle catches the entire width of the stitch.
Just like for tailoring sewing machine, for handmade work there is a whole arsenal of sewing needles. For different types works and materials, needles of the appropriate size and type are used. For light and thin fabrics, you need to use sharp and thin needles.
Hand stitches can be used in areas where a sewing machine cannot stitch. Either skipped stitches appear or the thread breaks. Leave this section and continue sewing the zipper. Select a needle and use the same threads that are in the spool on the machine to imitate a machine stitch using hand stitching.
Hand stitches are not used when sewing curtains. Curtains should have only machine stitching everywhere. Hand stitches made even an experienced craftswoman, will always differ from neatly stitched machine stitches.
You can't hem jeans with just any sewing machine. Sewing machine breaks needles on rough, four-layered areas of jeans. It's time to remember about hand stitches and hem your jeans with one of these hand stitches.
When sewing covers, it is sometimes necessary to protect the inner edges from fabric “spillage”. Very loose fabrics may “crawl” after washing the cover. To prevent this from happening, use a hand stitch to edge the fabric. Using wide, not too frequent stitches, reinforce the cut edges of the cover parts.
So these are also skills that most people around us possess to one degree or another. Probably everyone has sewn on a button at least once in their life.
Now we will not touch upon the generally quite large list of hand stitches, but we will consider those that are, as they say, “well-known” and most in demand in this article.
Hand stitches
We will talk about seams, i.e. the connection of several (most often two) layers of fabric with one or several rows of repeating stitches of the same type.Hand seams are used both for a temporary purpose - connecting parts of products, and as permanent ones - for finishing sewing products, processing cuts, joining parts of products, sewing sewing accessories, etc.
Since hand stitches for temporary purposes are of an indicative nature - these are the contours of parts of patterns on the fabric, the directions of the lines of the middle of the shelves, backs, etc. and should be clearly visible on the material, they are laid with thin cotton threads of a color contrasting with the main fabric.
Threads of temporary hand stitches are removed by cutting the seam every 10-15 cm and carefully pulling out the ends of the threads.
When it comes to hand stitches permanent purpose, it is clear that they are laid with threads that match the tone (i.e., close in color) to the main fabric so that they are as less noticeable as possible on it.
The numbers of threads and needles are selected taking into account the type of fabric and the type of sewing operation (basting, hemming, etc.) that will be performed.
As well as in machine seams, when laying hand seams, a bartack is made at the beginning and end of each seam. Moreover, it does not matter what type of seams are laid - temporary or permanent.
You can simply tie a knot, but, as a rule, bartacks when laying hand seams are done by analogy with machine-stitched seams, using one of the proposed options.
1. The edges (cuts) of the parts to be joined are aligned. The needle is inserted into the fabric from the “back” side towards itself and is pulled, leaving a tail of thread 1-1.5 cm long.
2. When laying temporary stitches, make 1-2 stitches (stitch to stitch) of the bartack through the tap (cuts) of the parts being joined, and 3-4 stitches of the bartack when laying permanent stitches, holding the tail of the thread with your finger.
Depending on the type of stitches being laid - temporary or permanent - the tail of the thread is respectively either
remains, or is cut off and then the necessary seam is applied.
3. All actions are absolutely the same, with the exception of the fastening stitches, which in this case are laid parallel to the edges (cuts) of the parts.
0.5-0.7 cm before the end (or beginning) of the hand seam, a stitch is made in reverse direction, but the thread is not tightened to the end, a loop is formed into which the thread with the needle is drawn away from you and, without tightening the thread, the thread with the needle is now drawn towards you in the opposite direction into a tight loop, while carefully tightening the thread. Thus, a strong fastening knot is formed.
If this is the beginning of a hand seam, then a seam is laid next, and if this is the end of a seam, then before cutting the thread, the needle and thread are brought into the space of the seam allowances and cut.
This technique of thread cutting reduces the likelihood of the bartack unraveling.
Depending on the type of thread weave, hand stitches can be classified into straight, oblique, loop-shaped, cross-shaped and special.
With the exception of cross stitches and loop stitches, all hand stitches are made from right to left.
In addition to the fact that, regardless of the type of seams (manual or machine), if they are made with high quality, in addition to their main function - connecting elements, parts, units, etc., they also fully perform the function of finishing products.
This means that the seams from under the needles should come out even (in the sense of straight), with evenly tightened threads (unless otherwise specified in the seam laying technology) and with the same distance between the stitches.
The simplest and most frequently used are hand stitches made with straight stitches.
Running stitch (basting stitch) with straight stitches
It is used to temporarily connect parts (marking parts) and create assemblies.
Depending on the type of fabric I used and the type of sewing operation performed in which this seam is used, the length of the stitches is 0.2-5 cm. The running stitch is made with straight running stitches “forward with the needle”.
Temporary: as a rule, it is laid in front of the machine seam, so it is made at a distance of 0.1-0.5 cm from the contour of the future seam towards the cut, so as not to disturb the integrity of the seam, which will be laid by a sewing machine, when removed.
There are also some recommendations regarding the length of stitches on the front and back sides. So, for example, forming gathers, basting, basting, basting, basting, basting - all this is done with straight stitches of the same length (0.5-5 cm) on the front and back sides.
For applying control marks, fold lines, center lines of parts, etc. more often; In total, different-sized stitches 1-3 cm long are used.
This seam is used to transfer contour lines from one symmetrical side of the product to the other.
Copy seam perform as follows: parts of the product are folded front side inside.
Lay along the marked lines running stitches at a distance of 0.3-1 cm from each other, the thread is not tightened, but loops are made 1-1.5 cm high, depending on how thick the fabric is.
The loop is needed in order to be able to move the layers of fabric apart.
Copy stitches are laid strictly along the contours of the parts. After the running stitches are laid along the entire contour, the parts of the product are moved apart, and the stretched threads are cut in the middle. This way the contours are transferred to symmetrical parts.
That’s why bias stitches are called that because they are laid at an angle to the seam line.
Hand stitches with bias stitches are used when it is necessary that the cut details or layers of fabric do not move relative to each other in any way.
Among other things, hand seams with oblique stitches are much more elastic than hand seams with straight stitches, which does not interfere with the stretching of the fabric.
Oblique stitches are used to make hand stitches for temporary and permanent purposes. Temporary ones include basting (basting) and basting seams.
A basting seam with oblique stitches is used when basting collars, hems, etc.
When making basting seams, oblique stitches are laid with stitches parallel to each other, 0.7-2 cm long, from left to right.
The needle is pulled out of the material from the bottom up (as if towards itself) at a short distance from the edge of the parts and a stitch is laid along the surface of the upper part at an angle to the stitch line from top to bottom through all layers of fabric in the direction from the edge of the part.
The next needle puncture is made along the surface of the lower part from the bottom up through all layers of fabric along a line perpendicular to the edge of the parts being connected towards the stitch line. This creates a basting seam using oblique stitches.
The final step will be a machine stitch laid along the marked lines on the cut parts, after which it is necessary to remove all basting seams and turn the stitched parts or product right side out.
If it is necessary to secure the seams located inside the product, use a basting seam, which is performed similarly to a basting seam.
Most often, the basting stitch is used when processing patch yokes, pockets, collars, etc.
Just keep in mind that due to its remarkable feature of being “tightly” fixed, basting and basting seams are not recommended for use when processing parts made of fabrics with checkered and striped patterns and parts made of light, thin fabrics.
In the first case, wet-heat treatment may distort the pattern, and in the second, the structure of the fabric may change.
The stitches are directed freely, without tightening, the length of the stitches is 0.5-0.7 cm.
One of the representatives of manual seams with oblique stitches for permanent purposes is the overlock stitch, which is often used when it is necessary to process the edge (cut) of the fabric from fraying.
It is performed as follows: at a distance of 0.3-0.5 cm from the edge of the fabric, a needle is inserted into the material perpendicular to the edge from bottom to top from right to left.
This seam is used for permanent connection of parts in cases where it is very difficult (one might say impossible) to perform a machine stitch, when a seam of increased elongation (medium) is needed trouser seam) or when you need to secure the thread at the beginning or end of embroidery.
In any case, this is the most strong seam among all the hand stitches. The stitches are laid without breaks (gaps). The needle injection is made at the point where the needle exited the previous stitch.
On the seam line (a permanent seam is laid only in the indicated directions), a needle is pierced from top to bottom of all layers of material.
On the seam line along the part that is located below, a stitch is made forward and a needle is pierced through all layers of material, but from the bottom up. The distance between the entrance and exit of the needle is 0.1-0.3 cm.
On the seam line along the surface of the upper part, a stitch is made back, inserting the needle into the previous puncture of the fabric from top to bottom.
At the seam line, having brought the needle and thread out, the next stitch is made along the surface of the lower fly and the needle is pierced through the weight of the layers of material from the bottom up. The length of the stitch in this case will be twice as long, since the thread runs along the previous stitch and a new stitch is made.
Then the stitch is laid again, inserting the needle back (behind the needle) into the previous puncture. In this way, a stitched seam is formed using a needle.
Let's consider another type of seams, the essence of which is the same, but there are several options for execution. We are talking about seams that are part of a group called hemming seams.
Despite significant progress in the field of sewing technology, the area of processing the bottom edges of products cannot yet abandon handmade, and this is where hemming seams are most often used. Let's look at the most commonly used ones.
We remember that to make hemming stitches, the threads are selected to match the tone of the fabric (do not compare with visual illustrations, since for clarity only contrasting colors).
Whatever hemming stitch you choose, before you start working, you need to prepare the cut (edge) of the product for processing.
First, you need to bend the entire hem allowance of the product and fix it 0.5-1 cm from the fold in any way convenient for you (pin or baste).
Then bend the cut (edge) directly of the product allowance 0.5-1 cm from the cut (edge) and also fix it, stepping back from the edge of the resulting fold by 0.3-0.5 cm.
Iron both folds. The result is a folded edge with a closed cut. Now you can proceed directly to the hemming process.
A simple hemming stitch is used to secure a folded edge on the wrong side of a product, for example, to hem the bottom of a product.
It is performed as follows. The thread is secured in the fold of the hem allowance and further, capturing 1-2 threads from wrong side product in the direction from the wrong side of the product, the tip of the needle is brought under the seam allowance and the needle is brought out to the side of the seam allowance through the entire thickness of the folded cut at a distance of 0.3-0.5 cm from the fold of the folded cut.
The stitching direction is from right to left. And so on until the end of the treated area.
A blind hem stitch is used for the same purposes - to secure the processed part or hem the product on the wrong side of the product. The only difference is that it is done in such a way that the seam lines are not visible, neither from the front side nor from the back.
To do this, the folded edge with a closed cut is folded over to the front side of the product and the seam is laid along the front surface of the top fold of the hem allowance and along the back surface of the product no higher than the level of the top fold of the hem allowance.
The blind hem stitch is made from right to left. There are several ways to perform a blind hem stitch.
A blind seam with unequal blind loop stitches is made in this way - the hem allowance with a closed cut is folded to the front side of the product, 0.3-0.4 cm from the fold line of the upper cut of the hem allowance of the product, and a tack is made in the hem allowance, on a distance of 0.1-0.2 cm from the edge of the hem.
Again, with a slight tilt to the left, the needle is inserted into the surface of the front side of the folded cut (edge) of the hem allowance of the product 0.1-0.2 cm from the top fold of the hem allowance, passes between two layers of fabric: the hem allowance and the top fold hem allowance and is brought out after 0.5-1 cm again to the front side of the folded cut of the hem allowance.
That is, the needle passes only one layer of fabric - the top fold of the hem allowance and comes out of the same layer. And thus we move until the hem is completed. Do not tighten the thread.
And the second option - blind seam using identical loop stitches.
The technology for making this seam is similar to the technology for sewing with unequal hidden loop stitches.
The only difference is that when a needle and thread are inserted into the front side of the folded cut (edge) of the hem allowance, it does not stretch 0.5-1 cm, but only picks up 1-2 threads on this surface and returns back to the surface the wrong side of the product.
The needle seems to jump from the surface of the back of the product to the front surface of the fold of the hem allowance - back and forth, back and forth.
The task comes down only to control that the jumps (in the sense of picking up 1-2 threads) are uniform and asymmetrical relative to each other.
It doesn’t matter how the product is hemmed, it is important that the result in both cases (provided, of course, that the work is done efficiently) justifies the name of the seam - a hidden seam. The hemming thread is not visible either from the front side or from the back side.
The seam is used to fix hems of open, unprocessed sections of product parts or the products themselves made from fraying fabrics. This seam is from the “2 in 1” series, i.e. both the raw cut of the product is processed and the hem allowance for the product is fixed.
This seam has a unique technology: the seam itself moves from left to right, but the needle moves from right to left. And the needle jumps, as in the previous example, from one surface to another.
The hem allowance is folded over to the wrong side of the product, fixed (with pins or basting) and ironed, i.e. the wrong side of the hem allowance (hem) is aligned with the wrong side of the product.
WITH back side hem facing the wrong side of the product, a tack is made (in this case you can simply tie a knot) and the thread is brought to the front side of the hem from bottom to top at a distance of 0.4-0.5 cm from the raw cut.
Directing the needle point from right to left, i.e. in the opposite direction, with an inclination to the right from the thread exit, the needle picks up 2-3 threads on the surface of the wrong side of the product 0.2-0.3 cm above the raw cut and the thread is pulled through them.
Without changing the direction of the needle, from left to right, at a distance of 0.5-0.7 cm from the first needle puncture and at the level of the first needle puncture, 2-3 threads are picked up on the front surface of the hem and the thread is pulled through them.
This is how, alternating between picking up the threads from below and from above, a hemming seam is laid using cross stitches.
Source - Bible of Cutting and Sewing magazine
Welded metal joints are among the main methods of fastening structures used in everyday life and production. This is a very reliable method of obtaining a single design, which is also relatively cheap.
Bonds of this type are formed by melting the metal in the joint area and then crystallizing it as it cools. Their quality depends on the right choice operating mode of the electric welding machine, electrode, seam penetration. This is regulated by current regulations and standards. They indicate all types of welds, as well as types of joints and their characteristics.
Numerous metals have their own welding characteristics, different work conditions, and requirements for fastening. For them, appropriate types of electric welded connections are used. When welding metal elements, the main types of electric welding fasteners are used, which are discussed below.
Classification
Welding joints are divided into several varieties, depending on their characteristics. The classification of welds covers the entire range of their uses. According to external parameters they are:
- convex type (with reinforcement);
- concave (weakened design);
- flat type (normal).
According to the type of execution, they are found one-sided, as well as double-sided, according to the number of passes with the electrode: single-pass, double-pass. In addition, there are single-layer and double-layer welding methods.
According to their length, suture fastenings are:
- single-sided with intermittent pitch;
- solid one-sided;
- spot (with contact electric welding);
- chain double-sided;
- double-sided checkerboard pattern.
Separation by spatial location:
- horizontal, lower;
- vertical, ceiling;
- into a boat;
- semi-horizontal design;
- semi-ceiling type;
- semi-vertical.
According to the force vector:
- longitudinal (flank) – the force has a vector parallel to the penetration;
- transverse - the force acts perpendicularly;
- combined - a type of frontal, as well as flank;
- oblique - the impact occurs at an angle.
According to their purpose and function, electric welding penetrations can be durable, as well as durable and tight, hermetically sealed. By width they are distinguished into thread type, not exceeding the diameter of the electric welding electrode rod, and widened, performed using oscillatory movements when welding in the transverse direction.
To simplify the understanding of the classification and application of certain varieties, a special table has been compiled.
All types of seams have a strict designation according to GOST. The drawings use special icons that contain complete information about the type of fastening and its method of execution. For those who are thinking of seriously engaging in welding work at a professional level, they should additionally study the drawing symbols of welded fasteners.
Types of welds
Depending on the material used, thickness, as well as design features, they are used Various types welds. To do this, you need to undergo the necessary theoretical training. This will allow you to better understand the specifics of welding parts and avoid defects in work. Novice welders often do not sufficiently weld the joint areas, which affects the weak mechanical resistance of the joints. Choosing correct modes works and types of welding, it is possible to obtain welding seams of sufficient strength and quality. Welder training is not only about practical exercises, but also in theoretical training with the study of requirements, norms and rules, as well as including the types of welding joints and equipment used. Knowledge of the principles of using certain electric welding fasteners, the techniques for producing them, the joints will be very strong and durable.
Butt
This connection option is the most used among other types of welding seams. This butt welding is used on end sections, pipes or sheet metal structures. To obtain it, a minimum amount of time, material and effort is spent. These butt joints have some seam features. On thin sheet metal, welding is carried out without bevel of edges.
Products with large thickness of joint sections require preliminary preparation of joints, which consists of beveling them to increase the depth of welding penetration. This is necessary when the thickness of metal products is over 8 mm and up to 12 mm. Thicker sections must be joined by double-sided welding with preliminary bevel of the edges. Butt welding is most often performed on products in a horizontal plane.
T-bar
These types of electric welding connections are made like a regular letter “T”. They connect objects of the same or different thickness, which determines the width of the weld seam. In addition, these types are used single- or double-sided, which is influenced by the characteristics of the fastening. When working with metal elements of varying thickness, the electrode is held in an inclined position at an angle of about 60 degrees. The welding process can be greatly simplified by using tacks, as well as boat welding. This method significantly reduces the occurrence of undercuts. The T-weld is applied in one welding pass. In addition to manual arc welding, automatic electric welding machines are widely used for this type.
Overlapping
This method is used for welding sheet metal with a thickness of up to 12 mm. The areas to be joined are overlapped and welded along the joints on both sides. Do not allow moisture to enter inner part welded structure. To strengthen the bond, full welding is performed around the perimeter.
With this welding, the formation of a connecting joint occurs between the end of one product and the surface of another. With this type of welding seams and connections, the consumption of materials increases, which must be taken into account in advance. Before starting work, you should align the sheet structures and ensure that they are pressed well together.
Corner
These connections include fastenings of elements made at a certain angle to each other. They are characterized by the use of preliminary bevels to ensure the best weld penetration. This will increase the depth of the welding joint, which will increase the reliability of the structure. To enhance strength, double-sided welding of metal products is used, while gaps in the joined edges are not allowed. These types of electric welds are characterized by increased use of the volume of deposited metal.
Ceiling
Welding with a ceiling seam, the seam of which is located above the welder, is one of the most difficult types of electric welding work. It is applied by intermittent welding at a low electric current. Vertical and ceiling connections are very difficult, so not all welders can perform them with sufficient quality. They are used in places where it is not possible to change the position of the structures being welded. These are pipes, various metal structures, as well as ceiling beams and channels at construction sites. The specifics of making ceiling seams, the video of which will explain the nuances, can be mastered through constant practice.
Weld geometry
Having studied numerous types and methods of obtaining joints by welding, it is necessary to familiarize yourself with the geometry of the joints, which photos of welding seams will help with.
The main parameters of a seam joint include its width - e, welding thickness - c, convexity - q, gap - b, welding depth - h, and the thickness of the material being welded - S.
For corner joints, the following designations are used: convexity - q, thickness - a, leg - k and design height - p.
Various methods of applying welds, their numerous types, as well as the parameters of the prepared edges affect the volume of use of the deposited and base metals. Its quantity may differ markedly when any calculated values change.
Types of welding joints are characterized by a shape coefficient, which is calculated by the ratio of the width to the thickness of the seam joint. For butt fastenings, this parameter is in the range of 1.2-2 (limit values 0.8-4). The convexity coefficient is calculated by the ratio of width to convexity, the value of which should be from 0.8 to 4.
Welding metal materials at an angle relative to each other requires precise adherence to the geometry of the seam. The reliability of the connection, as well as its durability of use, directly depends on the quality of welding and compliance with the required parameters.
Types of control
The further operation of the structure depends on the high-quality execution of electric welded fastening. Various defects significantly reduce the strength and reduce the period of use of the product. To prevent marriage, as well as to prevent emergency situations Various types of weld inspection are used. These include an external examination, which can visually determine violations, their types, as well as the use of special equipment to determine hidden defects welds.
Control methods are divided into non-destructible and destructible. When using the first method, the strength of the welded joint is determined without changing it appearance, parameters. Destructible methods are used for mass production of structures using the same type of electric welding work. This provides an opportunity with high accuracy identify internal violations of welding bonds.
Download GOST
Permanent hand stitches are used when sewing clothes or any other fabric product. For example, a back and forth needle stitch can replace straight machine stitching in small areas. The edges that are inaccessible to the machine are processed using an “over-the-edge” seam and an overcast seam.
A straight seam, more often used to secure folds. The seam is simple, but not very reliable. Work from right to left, sticking the needle in and out several times before pulling the thread through. Stitch length 3 mm.
Durable seam used instead of machine stitch. From right to left, make a small stitch. Insert the needle into the beginning of the previous stitch and pull it through the front of the thread. Sew the next stitches in the same manner, inserting the needle at the end of the previous stitch.
A strong stitch that can be used for both overcasting edges and sewing together multiple layers of fabric. From right to left, pierce the fabric with a needle, from bottom to top, stepping back a few millimeters from the edge. Continuing the seam, move to the left.
Used for invisible sewing of zippers. From right to left, make a small backward stitch, pulling the needle 6-10mm to the left of the thread. Next, make the same tiny backstitch stitches.
Used for butt joining 2 layers of fabric. From right to left, sew a 6mm stitch inside the folded edge of one fold. Then make the same stitch inside the folded edge of the other fold.
Used for processing the edges of non-flowing fabrics. From right to left, stepping back a little from the edge, pierce the fabric with a needle from bottom to top. Step back a little to the left and pierce the fabric again from bottom to top.
A decorative stitch used instead of stitching along the top. From right to left, make a small backstitch, picking up a few threads from the fabric. Back off 7-10 mm and remove the needle, grasping only upper layer fabrics. Repeat.
In this article we have described almost all the main manual permanent sutures, we will write about temporary hand stitches in the next article.
This post is posted in the category tagged .