Check the cart for specific shipping classes, remove Free Shipping if they are present

gistfile1.php

/**
 * Check the cart for specific shipping classes, remove Free Shipping if they are present
 *
 * This code will remove free shipping if a product is in the cart that can not be delivered for free
 * Assign a shipping class to those products and add the slug to the $freeshipping_array
 * Multiple shipping classes can be added to the array
 *
 * Add the code to your theme functions.php file
 */
add_filter( 'woocommerce_package_rates', 'unset_free_shipping_when_product_in_cart' , 10, 1 );
function unset_free_shipping_when_product_in_cart( $available_methods ) {
	
	/**
	 * Set free shipping variable to true
	 * 
	 * Free shipping is allowed unless we find a product with a shipping class that 
	 * does not allow free shipping
	 */
	$freeshipping = true;
	
	// Setup an array or shipping classes that do not allow free shipping
	$freeshipping_array = array( 'local-delivery' );
	
	// loop through the cart checking the shipping classes
	foreach ( WC()->cart->get_cart() as $cart_item_key => $values ) {

		$shipping_class = get_the_terms( $values['product_id'], 'product_shipping_class' );

		if( in_array( $shipping_class[0]->slug, $freeshipping_array ) && $freeshipping ) {
			$freeshipping = false;
			break;
		}
	}

	// Unset Free Shipping if necessary
	if( $freeshipping == false ) {
		unset( $available_methods['free_shipping'] );
	}
	
	return $available_methods;
}

Thanks so much for this.. I tried on the latest version 2.4.6 and it no longer seems to work. I'm adding an item with a 'Heavy' Shipping Class to the basket. I want to remove the Free Shipping option (applied normally if buying over £10.00) IF the Basket contains a 'Heavy' shipping item along with regular items and the total is over £10.00.

I am using a Variable Product with a Shipping Class so although don't think this would have any effect worth a mention. I apologise if I shouldn't write a comment here. Please delete if not appropriate.

Update... now seems to be working. FYI did three things.
WC>System Status>Tools>Clear Transients. (Checked after and no change).
Cleared Basket - re added items. (Checked after and no change).
Re-Updated the Variable Product with Heavy Shipping Class applied. (This seemed to do it, though think it may have been a combination of all three as would have obviously updated\saved this when originally applying the Shipping Class?)

Worked great until the update to 2.6.
Did they changed the hooks with the new "shipping zones"-feature?

This should help re Woo update to 2.6.

I amended part of the original code above to that as below. I removed the var_dump comment to see on the front end what is used and find the names (note; you'll need to check instance ID as will be different). Then I Unset as normal (though I needed to add two in as I've got free delivery in more than one zone). Hope this helps.

// Developers!: Dump this to see what you can unset // var_dump( $available_methods ); // Unset Free Shipping if necessary if( $freeshipping == false ) { unset( $available_methods['free_shipping:5'], $available_methods['free_shipping:6'] ); }