Surface Engineering FAQ: Solving Blasting & Shot Peening Issues.

Why my cycle timing has been increased in the blaster?

Assuming nothing else changed and parts are loaded accordingly with the best practice for your specific task:,

• Wheel Blaster: it may be media missing inside the machine. You can check the Amps, to variate is normal within a gap plus/minus 1; bigger gaps require further checks; if Amps are lower than expected you need to add new media, if wheel Amps are consistent you should check the media mix, maybe too dusty, settling the air washer if installed.

• Air Blaster: assuming media quantity is ok inside the machine, air flow is missing consistency, and nothing else has been changed.

  
  

Tech insight: the process is set for a certain amount of media (kgs or lbs) to be sprayed in a certain amount of time by wheel speed or air pressure. Assuming the wheel speed is ok is leaking the media - you see by the Amps fluctuating; much more common in air blaster is leaking air consistency - you see by pressure gauges. If speed, air pressure and media quantity are ok, it is missing the energy given by the media because doesn't have enough mass, so it is too dusty. Learn more about media consumption here.

Why Almen strip is not getting saturated as usual?

Why Almen strip is getting the same peening intensity?

Assuming nothing else has been changed, make sure your strip is ok by checking with another one, make sure your measuring device has been initialized properly; if you feel it should be ok try another Almen strip from another bag/box - different production batch. Are you sure the last media load in the machine was done with the right product?

Make sure the strip is where it is supposed to be, as position and fixture, check if somehow there is anything covering from the media shot flow.

• Wheel Blaster: check the wheel Amps while the process is ongoing, variation plus/minus 1 Amp ok, more needs further checks. Is the media enough inside the machine? If so check the washer, probably is too dusty; clean it and refresh with new media.

• Air Blaster: check the air flow by pressure gauges, if they are flctuating fix the air flow; check the media, is it enouhg? If so, check its quality, if it is too dusty set washer or replace the entire media inside.

  
  

Tech insight: the process is set for a certain amount of media (kgs or lbs) to be sprayed in a certain amount of time by wheel speed or air pressure. Assuming the wheel speed is ok is leaking the media - you see by the Amps fluctuating; much more common in air blaster is leaking air consistency - you see by pressure gauges. If speed, air pressure and media quantity are ok, it is missing the energy given by the media because doesn't have enough mass, so it is too dusty. Learn more about media consumption here.

Why glass molds and blanks are coming out dirty from the blaster?

Assuming nothing has changed, and you prolonged cycle time without success, you may first read here. Are you loading your molds (or moulds) as the best practice prescribe? Pic⬇️.

Glass molds and blanks correctly loaded inside the blaster.

Assuming all the above is ok, you should check protections and liners inside the cabinet, how old them are? Inexpectedly worn out? It may be related to uncorrect wheel flow alignment, check if possible to adjust it with a settling part like a regulator, should be in the media inlet area of the wheel. Position should be set accordingly with the media in use.

Tech insight: what is making the job is a combo of media sprayed witht the parts in the right position, assuming media is ok, as per the answer and its links, please check carefully how you are loading the machine, cycle time should be between 3 and 5 minutes, more there is something further to check. Learning more on media consumption here, leaning more on process drifting here. Full analysis on glass molds cleaning here.

Does shot peening improve fatigue life?

The short answer is yes. Fatigue life evaluates the lifetime of a part loaded cyclically lower than the static limit of the material the part is made of. It improves because shot peening introduces a compressive plastic residual stress layer on the surface. This acts as a shield against crack propagation, the typical failure by fatigue.

Shot Peening chart.

It is measured by Almen intensity and it is always related to a specific part, while the static limit is related to the material.

If you are looking for something more applicable, here is more about the process and here is about its business impact.

Extrusion die cleaning.

How to clean extrusion dies?

Four ways are the more popular among the industry:

• Manual Air Blasting: cheap to buy, expensive to run, no consistency, environmentally ok.

• Automatic Air Blasting: expensive to buy, expensive to run, almost consistent, environmentally ok.

• Wet Blasting: average to buy, expensive to run, consistent, environmentally bad

• Wheel Blasting: expensive to buy, cheap to run, very consistent, environmentally ok.

• Ultrasonic/Chemical: cheap to buy, average to run, consistent, environmentally bad.

Learn more here.

How to clean extrusion dies without damage?

Keeping the parameters under control, wherever technology is in use.

Wheel blasting is by far the safest from the damage perspective. Learn more here.

What is the best way to clean extrusion dies?

Wheel blasting by far is the best process, chosing the right media is part of the game too.

Learn more here. 

How to reduce extrusion die cleaning time?

Assuming it was shorter in the past, setting the machine as it was at the very beginning is always a good way to start, accordingly with the technology installed. Remeber to use the same media as well in case is needed; some tips for wheel blaster and air blaster.

Why do Amps readings fluctuate in wheel blasting or peening?

In a stabilized process, a fluctuation of ±1 Amp is considered normal tolerance. If the variation is wider, it indicates a lack of consistency in energy transfer.

1. Electrical Stability Fluctuations can originate from the feeding line. Check for "on-spot" devices on the same circuit that might create electrical noise. If the motor's power supply is inconsistent, the wheel’s RPM—and consequently the media velocity—will drift.

2. Media Flow Dynamics (Mechanical) The most common cause is an inconsistent media head in the storage hopper.

• The "Vortex" Effect: While the machine is running, check the hopper. If you see a funnel-shaped "vortex" at the outlet, the media level is too low. The valve is sucking air along with the media, causing "slugs" of abrasive rather than a steady flow.

• Inadequate Recharge: Ensure the storage remains at least 70% full during the entire cycle. If the hopper empties and refills intermittently, the Amp reading will bounce.

  
  

Technical Insight: Amperage is the direct proxy for Mass Flow Rate. Consistent Amps = Consistent mass of media thrown at a constant speed = Consistent Energy.

• For Blasting: Inconsistency leads to inefficient cycles and wasted Opex.

• For Shot Peening: It is a process failure. Inconsistent Amps mean you are failing to reach the required coverage and Almen intensity, compromising the design quality standard.

Understanding Shot Peening: Purpose, Mechanics, and Fatigue Strength.

What is shot peening and how does it work?

Shot peening is a controlled cold-working process used to increase fatigue strength and prevent stress corrosion cracking. Unlike cleaning processes, its purpose is to strike a metal surface with spherical media (shot) at high velocity, causing local plastic deformation.

How it increases fatigue life?

Each impact creates a small dimple on the surface, inducing a permanent layer of compressive residual stress. This layer acts as a barrier that prevents crack initiation and propagation—the primary causes of mechanical fatigue failure. The effectiveness of the process is strictly measured by Almen intensity and coverage percentage.

Can mechanical etching replace caustic chemical etching in Aluminum anodizing?

NO! Short answer. Etching is needed to activate chemically the aluminum surface before the proper anodizing process; where mechanical etching wins is shortening the chemical etching time by 90%, so the chemical waste produced, so not "eating" aluminum weight and removing all the surface defects.

Tech insight: anodizing is an electrichemical process to finish aluminum, popular among profiles and other parts; pretreatment of the anodizing process is a caustic bath to uniform the surface removing the defects ( for example extrusion lines) and to activate chemically the surface. Splitting the pretreatment in two parts is beneficial for specific cases.

Is shot peening expensive?

It depends on the application field and the specific technical requirements. In highly regulated sectors like aerospace or medical, costs are driven by strict compliance with international standards (e.g., AMS2430), requiring rigorous process monitoring and certification. However, if you are developing for non-standardized applications, it is possible to achieve the desired results with a significantly optimized investment by focusing on the core parameters of your specific requirements.