Weld Time is the time during which welding current is applied to the work in making a weld. It is measured in cycles of line voltage as are all timing functions. One cycle is 1/60 of a second in a 60 Hz power system. Hold Time is the time during which electrode force is maintained on the work after the last

Apr 03, 2020· Welding aluminum in the wrong polarity/adjusting balance. This TIG weld (Figure 2A) was created with the machine’s polarity set on direct current electrode negative (DCEN). As you can see, the weld did not break through the aluminum oxide layer. This created a weld where the filler metal mixed in with the partially melted oxide and created ...

Welding aluminum is not as hard as you think. Turns out you can weld aluminum without a welder! This instructable will teach you how to use a propane torch and some aluminum brazing rods as a quick way to bond aluminum without using a welder. It makes for a very strong bond and with a little practice can be done quickly with great looking results.

Preheating the cast iron part before welding will slow the cooling rate of the weld, and the region surround the weld. It is always preferred to heat the entire casting, if possible. Typical preheat temperatures are 500-1200 degrees F. Don’t heat over 1400 degrees F since that will put the material into the critical temperature range.

Sep 20, 2017· Cold Heading Basics Cold heading (or cold forming) is a method of forming metal in progressive steps into net shaped or near net shaped parts. Starting with a slug, which is cut from a continuous coil of wire material; the cold heading machine uses a …

Welding, technique used for joining metallic parts usually through the application of heat.This technique was discovered during efforts to manipulate iron into useful shapes. Welded blades were developed in the 1st millennium ce, the most famous being those produced by Arab armourers at Damascus, Syria.The process of carburization of iron to produce hard steel was known at this time, but the ...

Cast Iron Repair - Goltens technicians are experts at repairing cast iron. Whether your requirement is repairing a cracked engine block or other cast component, call Goltens and see if we can salvage your valuable equipment with metal stitching.

Be Prepared: Five Potential Welding Safety Hazards to Avoid by John Petkovsek, Director, Environment, Health and Safety, The Lincoln Electric Company Safety is a critical consideration for any welding project. Arc welding is a safe occupation when proper precautions are taken.

Using the wrong welding electrode on cast-iron can result in many issues including a weak weld. This can lead to cracks in the joints which can cause leaks or weak spots that may cause a problem later during use. It is also important to note that when you are welding cast iron, it does not handle a severe temperature variation.

The Following Section consists Multiple Choice Questions on Workshop Technology. Take the Quiz and improve your overall General Knowledge.

Cold shuts appear as a distinct darkened line of variable length and definite smooth, (Heavier than Casting) outline. Cold shuts are formed when two bodies of molten metal flowing from different directions fail to unite and form homogeneous metal.

Casting Defects - Sand Mold, Metal Casting. Introducing various metal casting defects with many pictures by Dandong Foundry in China. These are the common sand casting defects on the surface and inside of cast iron and cast steel parts. 1. Blowhole and Pinhole This is a kind of cavities defect, which is also divided into pinhole and subsurface blowhole.

No cables may be used where splices are within 10 feet of the electrode holder. Do not coil or loop electrode-welding cables around parts of your body. Do not stand in water or on damp ground when doing electrical welding. Moisture connects your body to ground and may form the path of least resistance, causing a severe shock. Gas-Shield Arc Welding

Primary Processing Discontinuities - Casting • Cold shut – due to lack of fusion between two streams of . metal as it flows into the cast • Hot tear – due to difference in cooling rates between thin . and thick sections (a crack formed while the casting is cooling)

It is also called as cold shut. It is a crack with round edges. Cold lap is because of low melting temperature or poor gating system. This is not just surface defect.

Cold Shut links are used to repair low carbon steel chains, as well as installing coupling attachments. After sliding the cold shut link between two other links or an attachment, use a hammer to pound the end of the cold shut through the eye. To seal the link, you must peen the extended end of the cold shut, which prevents the link from opening.

Cold Cracking. Cold cracking is much worse than hot cracking simply because it may be hours or days before the crack appears. This means the welded assembly may already be out the door and in service. Cold cracking is characterized by a crack starting on the base material and not on the weld as is the case with hot cracking.

Finding casting materials in the Total Materia database. The Total Materia database contains many thousands of casting materials across a large range of countries and standards.. Where available, full property information can be viewed for materials including chemical composition, mechanical properties, physical properties, advanced property data and much more.

General Welding Discontinuities. The following discontinuities are typical of all types of welding. Cold lap is a condition where the weld filler metal does not properly fuse with the base metal or the previous weld pass material (interpass cold lap). The arc does not melt the base metal sufficiently and causes the slightly molten puddle to ...

cold shut A fold in rolled or forged metal closed (shut) by the process but not welded. A cold shut is the same as a crack except it has been caused by bad forging or rolling practice. Commonly mispronounced "cold shunt". copper Element number 29, symbol Cu, a metal (Latin, cuprum). A red ductile metal occasionally found in its native state.

2 days ago· Welding Machines range in size and weight from 20 to hundreds of pounds. Therefore, if you are going to be carrying your welder to different locations, compact and lightweight welding machine is most recommended. Frequently Asked Questions Q: What is welding? Welding is a process of joining two metals by heating until the two ends become molten.

Apr 24, 2017· Welding. Along with cutting, welding is one of the most popular metal fabrication processes among crafts enthusiasts. The process of welding involves the joining of two separate metal parts. The parts used in a welding application could be sheets, panels, bars or shapes — as long as the parts are made of metal, it really doesn’t matter.

Die Casting (Brit. Pressure Die Casting) A rapid, water-cooled permanent mold casting process limited to nonferrous metals. There are three types: the plunger-type operated hydraulically, mechanically, or by compressed air with or without a gooseneck; the direct-air injection which forces metal from a goose-neck into the die, and the Cold-Chamber Machine.

Oct 02, 2016· It is the basic defect which generally occurs. It is occur when the molten metal flow through two different paths. When the two stream of molten metal comes in contact and solidify before they mix completely, some bubbles form between them. This phenomenon is known as cold shut. It is also known as cold lap.

Cold Shuts in the Welding Process Cold shuts can occur in the welding process as well as with the casting process. When it occurs in welding, it may go by the name of lack of fusion. The principle remains the same as with cold shuts within the casting process.

Welding Interview Questions and Answers will guide us now that welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material the weld pool that cools to become a strong ...

Cold Shot: Small globule of metal embedded in, but not entirely fused with the casting. Cold Shut: A casting defect caused by imperfect fusing of molten metal coming together from opposite directions in a mold or due to folding of the surface. Collapsible Core: A metal insert made in two or more pieces to permit withdrawal from an undercut mold ...

Nov 11, 2017· Cold Shut It is a type of surface defects and a line on the surface can be seen. When the molten metal enters into the mold from two gates and when these two streams of molten metal meet at a junction with low temperatures than they do not fuse with each other and solidifies creating a cold shut (appear as line on the casting).

Apr 25, 2017· Today we will learn about forging defects types, causes and its remedies.Defects are common in every manufacturing process like casting includes casting defects, welding includes welding defects, same as forging consist some defects which are due to both process and human limitations. Forging gives better mechanical properties among all manufacturing process but it also …

Cold Lap is a condition where the weld filler metal does not properly with the base metal or the previous weld pass material (interpass cold lap). The arc does not melt the base metal sufficiently and causes the slightly molten puddle to flow into the base material without bonding. Figure 1: Cold Lap.

In addition to misruns, cold shuts are another common pouring defect many people run into during casting. Many novice casters mistake them for misruns, even though they are different. The difference between the two is how the metal pours into the mold. Instead of leaving a section of the mold empty, a cold shut leaves a noticeable crack.

Boundary between a weld face and the parent metal or between runs. This is a very important feature of a weld since toes are points of high stress concentration and often they are initiation points for different types of cracks (eg fatigue cracks, cold cracks).

Cold shuts occur when two fronts of liquid metal do not fuse properly in the mould cavity, leaving a weak spot. Both are caused by either a lack of fluidity in the molten metal or cross-sections that are too narrow. The fluidity can be increased by changing the chemical composition of the metal or by increasing the pouring temperature.

Types of forging defects include unfilled section, cold shut, scale pits, die shaft, flakes, improper grain growth, incomplete forging penetration, surface cleaning, and residual stresses in forging. Forging companies and workshops should take necessary measures to avoid these defects.

Jul 24, 2015· Solved Gate Questions on Casting Question 1. A 200 mm long down sprue has an area of cross—section of 650 where the pouring basin meets the down sprue (i.e. at the beginning of the down sprue). A constant head of molten metal is maintained by the pouring basin.

In this page you can learn various important welding questions answers,sloved welding representation questions answers, welding mcq questions answers etc. which will improve your skill.