LeBrew·
Why we need to replace the burrs?
Abstract
With prolonged use of a coffee grinder, its core components—the burrs—gradually lose their sharpness and begin to dull visibly. In some cases, chipping along the edges may also occur. This is particularly common in commercial espresso grinders, where burrs are subjected to heavy grinding loads, frequent cleaning, and repeated recalibration. Common wear issues include erosion in the triangular zone, coating degradation, and in severe cases, damage caused by foreign objects like stones, which can result in significant chipping. These problems ultimately lead to a loss of grind consistency.
Burr wear not only affects grinding efficiency and machine lifespan but also significantly alters the flavor profile and extraction stability of coffee. In this article, we present test data illustrating how worn burrs impact grind size distribution and offer practical guidance on when grinder burrs should be replaced.
Table of Contents
What Happens When Coffee Grinder Burrs Are Worn?
A well-maintained coffee grinder burr should stay sharp to ensure optimal performance and flavor. While most modern burrs come with wear-resistant coatings, these coatings cannot fully prevent dulling and chipping over time. In many cases, burrs begin to show significant wear after grinding approximately 1,500 kg of coffee beans—often resulting in coating loss, blade dulling, reduced efficiency, and irregular grind size distribution.
This level of wear is frequently seen in commercial espresso grinders. For instance, a Fiorenzato F83 used for 2–3 years may require 7 seconds to complete an espresso grind and still produce inconsistent particle sizes. This results in erratic extractions and unpredictable flavor profiles.
At LeBrew’s lab, we developed a worn burr simulation model to measure the impact of burr wear on grind size distribution. As shown in Figure 1, the left burr is worn, and the right is new. Using the LeBrew ParticleGo analyzer (Figure 2), we observed that worn burrs produced less stable particle distribution with higher fines content—both of which compromise grind consistency and flavor clarity.
Figure 1: Model of Worn Grinder Burrs
Figure 2: Particle Size Distributio
Under identical burr gap and grind speed conditions (10g of coffee at 1350 RPM), the results showed that worn burrs produced nearly twice as many fines, and the particle distribution became wider and more volatile.
This directly impacts grind uniformity, making brews harder to control and resulting in less consistent flavor expression. Worn burrs reduce adaptability across different brew methods, from espresso to pour-over.
When Should You Replace Coffee Grinder Burrs?
Here are five common signs that it's time to replace your burrs:
1. Over Two Years of Use & Inconsistent Extraction
If your grinder is in frequent use and has been running for over two years, it’s advisable to inspect the burrs. Worn burrs cause widened grind size distribution, leading to:
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Frequent espresso channeling
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Imbalanced flavors (sour and bitter separation)
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Fine particles clogging filters and slowing extraction flow
2. Coffee Grounds Feel Hot After Grinding
If the temperature of your espresso grounds rises noticeably, it may indicate that the burrs are dull and crushing rather than cutting. Increased friction leads to heat buildup, which can degrade coffee aromas. Replacing burrs can help preserve flavor integrity.
3. Loss of Control Over Brew Pressure or Flow Rate
If your grinder can no longer fine-tune extraction pressure or flow, or if grind range has narrowed and efficiency slowed, your burrs may be worn. Dull burrs limit particle size control and cause espresso extractions to become unstable.
4. Motor Overload or Frequent Overheating
Dull burrs increase motor load during grinding. If your grinder’s motor activates overload protection or if power draw noticeably increases, the likely cause is burr dulling. Continued use could damage or burn out the motor.
5. Physical Damage from Foreign Objects
If stones or metal fragments are accidentally ground with the coffee, chipping or nicking of the burrs can occur. If you hear unusual grinding noises or notice performance issues, stop the machine immediately and inspect the burrs. Any significant damage should prompt immediate replacement to avoid further harm.
🔍 Frequently Asked Questions About Worn Burrs
Understanding when and how to replace grinder burrs is crucial—but even experienced baristas and café owners often have lingering questions. Below are answers to some of the most common inquiries we’ve received from the coffee community regarding burr wear, grinding consistency, and machine maintenance.
Q1: How do I know if my coffee grinder burrs are worn out?
A1: You may notice longer grinding times, inconsistent grind size, increased fines, or unstable espresso extraction. Physical signs include dull edges, chipping, and coating wear on the burrs.
You may notice longer grinding times, inconsistent grind size, increased fines, or unstable espresso extraction. Physical signs include dull edges, chipping, and coating wear on the burrs.
Q2: When should I replace the burrs in my coffee grinder?
A2: For home use, consider replacing every 1–2 years depending on usage. For commercial use, replacement is often needed after grinding 1,000–1,500kg of coffee beans.
For home use, consider replacing every 1–2 years depending on usage. For commercial use, replacement is often needed after grinding 1,000–1,500kg of coffee beans.
Q3: What happens if I keep using worn burrs?
A3: Worn burrs cause uneven grind size, increase in fines, potential motor overload, poor flavor clarity, and inconsistent extraction with issues like channeling.
Worn burrs cause uneven grind size, increase in fines, potential motor overload, poor flavor clarity, and inconsistent extraction with issues like channeling.
Q4: Can worn burrs affect coffee flavor?
A4: Yes, dull burrs reduce grind consistency, leading to sourness or bitterness separation, weak body, and loss of sweetness in your coffee.
Yes, dull burrs reduce grind consistency, leading to sourness or bitterness separation, weak body, and loss of sweetness in your coffee.
Q5: Why does my coffee get hotter after grinding?
A5: If your coffee grounds feel unusually warm, it could mean the burrs are dull and creating friction by crushing instead of cutting, generating more heat.
If your coffee grounds feel unusually warm, it could mean the burrs are dull and creating friction by crushing instead of cutting, generating more heat.
Q6: How does burr wear affect espresso extraction?
A6: It narrows the grind adjustment range, makes it hard to dial in the right pressure and flow rate, and can lead to under- or over-extraction.
It narrows the grind adjustment range, makes it hard to dial in the right pressure and flow rate, and can lead to under- or over-extraction.
Q7: Can dull burrs damage the grinder motor?
A7: Yes. Worn burrs increase resistance during grinding, raising power consumption and triggering the motor’s overload protection, potentially damaging it over time.
Yes. Worn burrs increase resistance during grinding, raising power consumption and triggering the motor’s overload protection, potentially damaging it over time.
Q8: What causes sudden damage to burrs besides wear?
A8: Foreign objects like stones or metal in coffee beans can chip or crack burrs instantly. Always inspect for physical damage if you hear abnormal grinding sounds.
Foreign objects like stones or metal in coffee beans can chip or crack burrs instantly. Always inspect for physical damage if you hear abnormal grinding sounds.
Q9: How do coated burrs help, and can they still wear out?
A9: Coated burrs (e.g., titanium or DLC) offer improved durability, but they still wear out over time and require replacement after heavy use.
Coated burrs (e.g., titanium or DLC) offer improved durability, but they still wear out over time and require replacement after heavy use.
Q10: What tool can I use to check grind consistency changes?
A10: Devices like the LeBrew ParticleGo particle analyzer can measure grind size distribution and help you detect inconsistencies caused by worn burrs.
Devices like the LeBrew ParticleGo particle analyzer can measure grind size distribution and help you detect inconsistencies caused by worn burrs.
The design of a coffee burr is a complex system. A good burr requires careful consideration from multiple aspects. LeBrew offers diverse flavor performance possibilities, enabling boundary-breaking grinding from espresso to filter.
Have Questions or Suggestions?
If you have any feedback or would like to know more, feel free to contact us at:
service@lebrewtech.com
