Clean and Lubricate the Spherical Seat on Your AFGB1

“I hate cleaning my machine!  It’s such a dirty job.  And, it doesn’t make a difference anyways, does it?”

Does it?  Actually, it does make a difference.  Keeping your gyratory compactor clean and free of debris will reduce wear and ensure maximum performance.  Let’s consider only one specific part of the AFGB1, the spherical seat.

Why should you care about the spherical seat? 

  1. Worn spherical seats and molds eventually need replaced, which is an expensive proposition that could likely have been delayed if they had received proper attention. 
  2. As the spherical seat and the mold wear, the mold sits lower in the compaction chamber.  This causes a higher angle of gyration, which can lead to issues with specimen density.

The spherical seat is located at the bottom of the compaction chamber of an AFGB1, just beneath the pressure plate.  It supports the mold placed in the compaction chamber to make a specimen (Figure 1).

Figure 1:  Mold / Spherical Seat / Pressure Plate.

Mold clamps hold a mold firmly against the spherical seat during compaction.  As the machine gyrates, the mold slides against the spherical seat.  Cleanliness eliminates abrasive agents like aggregate particles that accelerate wear on the surfaces.  Lubricant reduces friction between the parts. 

Procedure U in Section 5.1.5 of the AFGB1 Operation Manual gives step-by-step instructions for cleaning and lubricating the Spherical Seat, which Pine recommends doing every 6 specimens or once a day. 

Pine’s video on lubricating an AFGB1,, provides guidance for complete lubrication of an AFGB1, including the spherical seat.

Keeping the beveled edge on the bottom of molds free of debris is important as well.  Wipe clean any surface before setting a mold on it.  Wipe clean the bottom beveled edge of a mold before placing it in the compaction chamber.  Aggregate particles stick to the lubricant and end up in the mold/spherical seat interface.

Giving attention to the mold/spherical seat interface by keeping it free of debris and properly lubricated can reduce maintenance costs and improve the performance of your AFGB1.

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