Why do we need to calculate Weld Deposition Rate?
The costs of any manufacturing process such as welding, machining, or cutting, etc. can be accurately calculated using the right approach and considering the essential related expenses & overheads. For welding cost calculation, one of the important factors is the rate of weld deposit per hour. Other factors for welding cost calculations are:
2. Welding consumables- Electrode, filler wire, flux, etc.
3. Overhead expenses
Before bidding for a project, cost analysis is the prerequisite to reaching a competitive selling price to win a project related to welding. The method given here is related to the calculation of the welding deposit rate only which is one of the factors related to finding the welding cost. Here, the most common welding deposition rate calculation methods are given.
Many times we as a Welding Engineers find ourselves in a situation looking for answers:
- How many Kilogram of welding rods I can deposit/hr?
- What is the wire deposition rate at different welding amperage settings?
- What will be the cost of welding wire for a project?
- What will be the cost of Welding jobs for a particular client?
Deposition rate (DR) vs. melt off rate (MOR)
Before you use this calculation, it’s important to understand the difference between weld deposition rate & MOR, as both are different terms. Deposition rate (DR) in welding refers to the speed with which a welding rod/wire is melted and deposited as a weld. The Unit of DR is pounds per hour or kg/hr. Whereas, the Melt-off rate (MOR) is the total weight of the welding consumable fused in a unit of time. Melt-off rate is also given in terms of lb/hr (pounds per hour) or kg/ hr.
Formula for Weld Deposition Rate Calculation
Deposition Rate = X x (D²) (FR)(Y) in pounds/ hour
- d = Dia. of welding rod
- FR = Wire-feed rate (inches/minute) in case of GMAW/ SAW/FCAW- consider electrode burn-off rate for stick welding or SMAW.
- Y =Electrode Efficiency,
- X =13.1 (Constant for Steel based on steel density. This constant is applicable for carbon steel and stainless steel welding filler wires. For Aluminum the value of A is 4.32).
Calculate the weld deposit rate for carbon steel pipe welding using GMAW with a wire-speed rate of 70 ipm (inch per minute) using an electrode diameter of 0.035 inches.
Calculation= 13.1 x 0.0352 x 70 x0.98 = 1.1 pounds/ hour.
Electrode Efficiency (Y) in Welding
Electrode efficiency (Y or also denoted by EE) is the Percentage of Melt-off rate (MOR) contributing to Deposition efficiency. EE for solid fillers can basically depend on the metal transfer mode in welding. As each metal transfer mode has varied characteristics that define how molten metal is transferred to the weld pool & associated losses during transfer such as spatters or metal vaporization. Listed below are the electrode deposit efficiencies for different metal transfer modes in GMAW:
- Short-circuit metal transfer Mode: 89-94%
- Surface metal transfer Tension Mode: 97%
- Spray metal transfer Mode: 97%
- Globular metal transfer Mode: 87 – 91%
- Pulsed metal transfer mode: 95- 98%
General Weld Deposit Rate in Different Welding Processes
The below table gives indicative weld deposit rates for SMAW, GMAW, FCAW, and SAW. As we know, various factors (current, electrode diameters, single or double electrode, welding position, metal transfer mode, etc.) influence the weld deposit rates, values stated here are for indicative purposes only.
Deposit rate in SMAW Process
E6010 x 3.2 mm @ 115 A … … … 1.25 kg/hr (2.82 lb/hr)
E6012 x 3.2 mm @ 115 A … … … 1.05 kg/hr (2.22 lb/hr)
E7014 x 4.0 mm @ 180 A … … … 1.82 kg/hr (4.0 lb/hr)
E7018 x 4.0 mm @ 180 A … … … 1.82 kg/hr (4.0 lb/hr)
E7024 x 3.2 mm @ 140 A … … … 1.41 kg/hr (3.1 lb/hr)
E7024 x 4.0 mm @ 210 A … … … 2.09 kg/hr (4.6 lb/hr)
Deposit rate in FCAW Process
E711T x 1.6 mm @ 275 A … … … 5.00 kg/hr (11 lb/hr)
E711T x 2.4 mm @ 400 A … … … 5.46 kg/hr (12 lb/hr)
Deposit rate in GMAW Process
ER70S-6 x 0.9 mm @ 175 A … … … 2.05 kg/hr (4.5 lb/hr)
ER70S-6 x 1.2 mm @ 175 A … … … 1.68 kg/hr (3.7 lb/hr)
ER70S-6 x 1.2 mm @ 225 A … … … 2.36 kg/hr (5.2 lb/hr)
ER70S-6 x 1.2 mm @ 270 A … … … 3.73 kg/hr (8.2 lb/hr)